Digital Forensics and the Tia Sharp Case - lect 19
Housekeeping
Course end surveys are available on Moodle.
Surveys can be found in the pop-out index on the right side of the screen.
The surveys are useful, and changes are made based on survey results.
The survey consists of five questions, including both likes and dislikes regarding the course.
Digital Forensics: Photo Response Non-Uniformity (PRNU)
PRNU was used in one of the first cases involving this technique.
The digital forensics unit in the MET was researching PRNU at the time. The unit was successful in its application to the case.
Further information is available in a publication by the lecturer on Moodle.
Tia Sharp Case: August 2012
Friday, 08/10/2012, was a significant date.
Tia Sharp disappeared in New Addington, near Croydon, South London.
Tia did not return from a shopping trip to her grandmother's house, and police were called.
Tia was 12 years old at the time and considered streetwise.
Police initially believed she would turn up, possibly at a friend's house.
A simple search of the house was conducted, but nothing was found.
Tia had left her phone behind, which was a red flag.
Initial missing person reports are typically handled by local police with limited resources.
The case was elevated to the CID after Tia didn't return by the next morning.
The CID conducted a more thorough search but found nothing.
Stuart Hazel, Tia's step-grandfather, claimed Tia went to Croydon on Friday morning - corroborated by a neighbor.
The inquiry was passed to a major crime team, leading to another house search by a trained police search team.
Reports surfaced of a man trying to lure young girls into his van, raising concerns about Tia's disappearance.
Tia's status was elevated to high risk, indicating serious concern for her safety.
Plans for Tia to go on holiday with a friend had fallen through.
The lecturer became involved when the case was passed to a major crime team.
The sergeant responsible for the search team indicated that they were primarily looking for Tia and may have missed subtle signs of harm.
Major inquiry teams have more resources, with about 30 to 40 people assigned to the search.
The public became heavily involved, searching wooded areas, open areas, and garages. The media also got involved, offering rewards.
The lecturer's request to research the house was initially denied due to multiple searches and the need to establish whether Tia had gone to Croydon.
Viewing CCTV footage from Croydon and public transport leaving New Addington was necessary to confirm Tia's whereabouts. Extra people were drafted to watch CCTV.
There were concerns that a forensic search would alter the focus and potentially impact a wider media search.
Police dogs searched the house inconclusively. A dog indicated a flag on the wall in Tia's room, but the indication was not understood.
The lecturer eventually obtained permission to search the house for evidence that Tia had come to harm.
There was a request for the forensic search to be obvious to show the police were doing everything they could.
The family was acting oddly and engaging in activities without police knowledge.
Stuart Hazel gave an unconvincing interview to the press, using past tense when referring to Tia.
The forensic search started on Friday afternoon, a week after Tia went missing.
The media was invited to observe the search.
The family moved out of the house due to the use of chemicals and equipment, such as luminol and lasers.
Stuart Hazel went missing after going out for paper.
A family liaison officer smelled a decomposing body while making a call on the landing due to bad mobile phone reception, and I was notified on the scene.
The SIO asked for the media to leave.
The SIO told me: "Andy, she's in the house. Go and find her."
The lecturer found it difficult to get near the house due to the press presence.
Standing on the landing, the lecturer couldn't smell anything.
The lecturer considered possible hiding places, such as the airing cupboard, under the bath panel, and the loft.
Ladders were brought to access the unlit and unboarded loft.
The loft contained bags, suitcases, and a disused water tank.
A shiny bin bag without dust was spotted in the corner of the loft.
The lecturer found a roll of bin bags wrapped around something wrapped in black fabric, which was a black fitted bed sheet.
A toe was visible when the elasticated part of the fitted bed sheet was moved.
The lecturer determined that there was a dead body in the loft.
The loft had high levels of insulation.
The temperature was 29 degrees Celsius when the lecturer was in the loft for four hours.
The clothing and glasses Tia was last seen wearing were found, along with a wrapper for a Knobbly Bobbly ice lolly.
Stuart Hazel was found drunk miles away and arrested after attempting suicide.
A post-mortem was inconclusive due to the condition of Tia's body.
The grandmother was also in custody waiting to be interviewed.
The house search took three weeks.
The local council decided to demolish the house.
A Sony digital camera was recovered from a kitchen drawer without a battery or memory card.
A memory card was found concealed within a crack in the door frame in the cupboard under the stairs.
Initial examination of the memory card showed very little content.
Extensive deleted pornography was recovered, including grade one images with young underage girls and obscene bestiality images.
Hazel would take pictures of his phone screen to save images he liked. His shadow or reflection was often visible in these images.
There were 11 still images of Tia sleeping and three video clips in her bedroom. He didn't do anything, just wanted to video her while she was asleep.
Professional-type pornographic photographs with young teenage girls wearing glasses, and an image of a young naked girl lying on Tia's bed.
The pathologist spotted lividity on the back of Tia's legs, which wasn't consistent with the position she was in, and determined that the female was dead when the picture was taken.
The plan was to see whether the pathologist could identify as being Tia in the image. He could not really but was concerned that his in his opinion, the female was dead when the picture was taken.
The pathologist determined the level of physical developement was consistent with someone of Tia's age. Also spotted lividity on the back of Tia's legs.
It was necessary to prove that the picture was taken on the recovered camera and to sequence the images.
The lecturer asked the digital policing about photo response non uniformity.
It's important to show that images were taken by known cameras.
The camera wasn't being made anymore. Ten identical cameras were found. Fifteen thirtytwo images were taken, and the lecturer did what they could to find the digital fingerprints the sensor leaves behind.
The camera sensor's profile is established by averaging patterns from a large number of bright, smooth test images. The PRNU pattern extracted from the questioned image is also looked at.
Sample images were obtained from similar cameras and compared with the camera's PRNU profile.
PRNU would give a probability, a likelihood ratio, a bit like you do with DNA.
The profile had some constant features and small areas of detail that changed each time the sensor was exposed to light, allowing the sequencing of images.
The process involves generating a camera PRNU reference pattern, extracting PRNU information from an image, and calculating the similarity for matching.
The examination showed conclusively that the target profiles match the recovered camera. It must be concluded at the highest level that both images have been produced by the same camera. The result also proved that the image of the girl on the bed was the last image taken by the camera.
Trial started. The images were shown in open court, which was unusual.
Stuart Hazel decided to change his plea. He pled not guilty, maintaining that Tia had fallen down the stairs and broken her neck, that he panicked, didn't know what to do, couldn't think how to tell her grandmother, so he hid her in the loft. He said that he had planned to move her but was not able to due to media frenzy.
He said that he wasn't able to move the body out of the loft because the media presence was so great.
He went missing because he could smell the decomposing body.
The grandmother thought something smelled because the cat had gone to the toilet somewhere and she hadn't had a chance to find it yet.
The judge went on to consider his verdict after about four hours of arguments, as the key point of argument was whether Tia was actually dead in the picture (to prove a greater chance of a whole life tarriff versus an ordinary life sentance). He sentenced Stuart Hazel to life imprisonment with a minimum term of thirty-eight years.
Housekeeping
Course end surveys are available on Moodle to gather student feedback. Encouragement for all students to participate.
Surveys can be found in the pop-out index on the right side of the screen, making them easily accessible.
The surveys are useful; student feedback directly informs changes and improvements to the course content and delivery.
The survey consists of five questions, including both likes and dislikes regarding the course, providing a balanced view.
Digital Forensics: Photo Response Non-Uniformity (PRNU)
PRNU was used in one of the first cases involving this technique, showcasing its early adoption and importance.
The digital forensics unit in the MET (Metropolitan Police) was researching PRNU at the time of the case, indicating proactive engagement with forensic technology.
The unit was successful in its application to the case, validating the effectiveness of their PRNU research and methodology.
Further information is available in a publication by the lecturer on Moodle, offering additional resources for interested students.
Tia Sharp Case: August 2012
Friday, 08/10/2012, was a significant date as it marked the beginning of the investigation.
Tia Sharp disappeared in New Addington, near Croydon, South London, triggering a large-scale missing person inquiry.
Tia did not return from a shopping trip to her grandmother's house, and police were called, initiating the formal investigation process.
Tia was 12 years old at the time and considered streetwise, influencing initial assumptions about her disappearance.
Police initially believed she would turn up, possibly at a friend's house, leading to a somewhat delayed escalation of the investigation.
A simple search of the house was conducted, but nothing was found, causing early investigative challenges.
Tia had left her phone behind, which was a red flag, suggesting her disappearance was out of character.
Initial missing person reports are typically handled by local police with limited resources, affecting the scope and intensity of early search efforts.
The case was elevated to the CID (Criminal Investigation Department) after Tia didn't return by the next morning, indicating growing concern.
The CID conducted a more thorough search but found nothing, increasing the urgency of the investigation.
Stuart Hazel, Tia's step-grandfather, claimed Tia went to Croydon on Friday morning - corroborated by a neighbor, providing an initial alibi.
The inquiry was passed to a major crime team, leading to another house search by a trained police search team, and marking a significant escalation in resource allocation.
Reports surfaced of a man trying to lure young girls into his van, raising concerns about Tia's disappearance and potential abduction.
Tia's status was elevated to high risk, indicating serious concern for her safety and prioritizing the investigation.
Plans for Tia to go on holiday with a friend had fallen through, adding complexity to understanding her recent activities and state of mind.
The lecturer became involved when the case was passed to a major crime team, bringing specialized forensic expertise to the investigation.
The sergeant responsible for the search team indicated that they were primarily looking for Tia and may have missed subtle signs of harm, highlighting the challenges of comprehensive crime scene assessment during initial searches.
Major inquiry teams have more resources, with about 30 to 40 people assigned to the search, significantly enhancing investigative capabilities.
The public became heavily involved, searching wooded areas, open areas, and garages. The media also got involved, offering rewards, creating both opportunities and challenges for the investigation.
The lecturer's request to research the house was initially denied due to multiple searches and the need to establish whether Tia had gone to Croydon, reflecting concerns about forensic evidence contamination.
Viewing CCTV footage from Croydon and public transport leaving New Addington was necessary to confirm Tia's whereabouts. Extra people were drafted to watch CCTV, demonstrating the intensive effort to verify her movements.
There were concerns that a forensic search would alter the focus and potentially impact a wider media search, balancing investigative integrity with public relations.
Police dogs searched the house inconclusively. A dog indicated a flag on the wall in Tia's room, but the indication was not understood, representing a missed opportunity in early evidence assessment.
The lecturer eventually obtained permission to search the house for evidence that Tia had come to harm, paving the way for crucial forensic analysis.
There was a request for the forensic search to be obvious to show the police were doing everything they could, managing public perception and maintaining transparency.
The family was acting oddly and engaging in activities without police knowledge, raising suspicions and necessitating closer scrutiny.
Stuart Hazel gave an unconvincing interview to the press, using past tense when referring to Tia, increasing suspicions due to linguistic indicators.
The forensic search started on Friday afternoon, a week after Tia went missing, marking a critical phase in the investigation.
The media was invited to observe the search for transparency and public reassurance.
The family moved out of the house due to the use of chemicals and equipment, such as luminol and lasers, to maintain the integrity of the forensic processes.
Stuart Hazel went missing after going out for paper, heightening concerns and shifting the focus of the investigation.
A family liaison officer smelled a decomposing body while making a call on the landing due to bad mobile phone reception, and I was notified on the scene, leading to the discovery of Tia's body.
The SIO (Senior Investigating Officer) asked for the media to leave to secure the scene and maintain control over information.
The SIO told me: "Andy, she's in the house. Go and find her," directing the lecturer to lead the search within the premises.
The lecturer found it difficult to get near the house due to the press presence, underscoring the challenges of working in high-profile cases.
Standing on the landing, the lecturer couldn't smell anything, indicating the body was well-concealed.
The lecturer considered possible hiding places, such as the airing cupboard, under the bath panel, and the loft, systematically assessing potential locations.
Ladders were brought to access the unlit and unboarded loft, requiring specific tools to reach the concealed area.
The loft contained bags, suitcases, and a disused water tank, filled with various items complicating the search.
A shiny bin bag without dust was spotted in the corner of the loft, raising suspicion due to its unusual condition.
The lecturer found a roll of bin bags wrapped around something wrapped in black fabric, which was a black fitted bed sheet, revealing a carefully concealed package.
A toe was visible when the elasticated part of the fitted bed sheet was moved, confirming the presence of a body.
The lecturer determined that there was a dead body in the loft, leading to the official identification of Tia's remains.
The loft had high levels of insulation, contributing to the body's decomposition.
The temperature was 29 degrees Celsius when the lecturer was in the loft for four hours, highlighting the harsh conditions faced during the search.
The clothing and glasses Tia was last seen wearing were found, along with a wrapper for a Knobbly Bobbly ice lolly, providing definitive evidence linking the body to Tia.
Stuart Hazel was found drunk miles away and arrested after attempting suicide, confirming his culpability.
A post-mortem was inconclusive due to the condition of Tia's body, requiring additional forensic analysis.
The grandmother was also in custody waiting to be interviewed, investigating potential involvement or knowledge.
The house search took three weeks, illustrating the thoroughness and complexity of the forensic investigation.
The local council decided to demolish the house, sanitizing the site and preventing it from becoming a memorial or attraction.
A Sony digital camera was recovered from a kitchen drawer without a battery or memory card, representing a key piece of evidence.
A memory card was found concealed within a crack in the door frame in the cupboard under the stairs, indicating deliberate concealment.
Initial examination of the memory card showed very little content, necessitating advanced forensic techniques.
Extensive deleted pornography was recovered, including grade one images with young underage girls and obscene bestiality images, revealing Hazel's disturbing interests.
Hazel would take pictures of his phone screen to save images he liked. His shadow or reflection was often visible in these images, providing a linking him to the content.
There were 11 still images of Tia sleeping and three video clips in her bedroom. He didn't do anything, just wanted to video her while she was asleep, indicating a disturbing pattern of behavior.
Professional-type pornographic photographs with young teenage girls wearing glasses, and an image of a young naked girl lying on Tia's bed, connecting Hazel to explicit materials and a crime scene.
The pathologist spotted lividity on the back of Tia's legs, which wasn't consistent with the position she was in, and determined that the female was dead when the picture was taken, proving the image was post-mortem.
The plan was to see whether the pathologist could identify as being Tia in the image. He could not really but was concerned that his in his opinion, the female was dead when the picture was taken.
The pathologist determined the level of physical developement was consistent with someone of Tia's age. Also spotted lividity on the back of Tia's legs.
It was necessary to prove that the picture was taken on the recovered camera and to sequence the images, reinforcing the forensic timeline.
The lecturer asked the digital policing about photo response non uniformity.
It's important to show that images were taken by known cameras, validating the authenticity of the evidence.
The camera wasn't being made anymore. Ten identical cameras were found. Fifteen thirtytwo images were taken, and the lecturer did what they could to find the digital fingerprints the sensor leaves behind.
The camera sensor's profile is established by averaging patterns from a large number of bright, smooth test images. The PRNU pattern extracted from the questioned image is also looked at.
Sample images were obtained from similar cameras and compared with the camera's PRNU profile.
PRNU would give a probability, a likelihood ratio, a bit like you do with DNA.
The profile had some constant features and small areas of detail that changed each time the sensor was exposed to light, allowing the sequencing of images.
The process involves generating a camera PRNU reference pattern, extracting PRNU information from an image, and calculating the similarity for matching.
The examination showed conclusively that the target profiles match the recovered camera. It must be concluded at the highest level that both images have been produced by the same camera. The result also proved that the image of the girl on the bed was the last image taken by the camera.
Trial started. The images were shown in open court, which was unusual.
Stuart Hazel decided to change his plea. He pled not guilty, maintaining that Tia had fallen down the stairs and broken her neck, that he panicked, didn't know what to do, couldn't think how to tell her grandmother, so he hid her in the loft. He said that he had planned to move her but was not able to due to media frenzy.
He said that he wasn't able to move the body out of the loft because the media presence was so great.
He went missing because he could smell the decomposing body.
The grandmother thought something smelled because the cat had gone to the toilet somewhere and she hadn't had a chance to find it yet.
The judge went on to consider his verdict after about four hours of arguments, as the key point of argument was whether Tia was actually dead in the picture (to prove a greater chance of a whole life tarriff versus an ordinary life sentance). He sentenced Stuart Hazel to life imprisonment with a minimum term of thirty-eight years.