After the lunch recess, the direct examination of LAPD Detective William Roecker continued, as he further explained how Burke’s cellular records and Tesla data allegedly tie him to locations where evidence was found after the murder of 14-year-old Celeste Rivas Hernandez.
Burke was seen smiling, nodding, and casually speaking to his attorneys Marilyn Bednarski and Blair Berk prior to the afternoon proceedings. Throughout the course of the week, he has remained relaxed, calm and nonreactive.
Detective Roecker finished his direct testimony by detailing that he reviewed multiple sources to determine when Burke’s Tesla was last driven. According to his analysis, surveillance footage, license plate reader data and Tesla records, the vehicle was not moved or driven between 2 p.m. on July 29, 2025, and September 5, 2025, when investigators ultimately recovered it. This corroborated previous law enforcement testimony about the last time the Tesla was driven.
During cross-examination, Marilyn Bednarski focused on what the defense perceived as limitations of Detective William Roecker’s cellular analysis. Bednarski established that Roecker’s analysis in this case was based on call detail records and Tesla IMSI records obtained from cellular carriers and not GPS data. Roecker also confirmed he reviewed records associated with Celeste Rivas Hernandez’s phone but did not personally examine the device for any GPS information.
He also testified that he did not conduct any drive testing in this case, explaining that his conclusions relied on timing advance data and cell tower records rather than “field testing.” When pressed about the precision of his analysis, Roecker agreed that the records could not point to an exact latitude or longitude, but maintained they provided accuracy of how far a device was from a particular cell tower. Bednarski pulled up one of the maps showing cellular activity near Burke’s Doheny Drive residence. Roecker agreed that based solely on the cell tower data, he could not state that Burke’s phone was conclusively at the residence. He explained that the records showed the device was “consistent with being in the area of Doheny Drive.”
Bednarski also elicited testimony that the records technically could not identify who was inside the vehicle or who was definitively driving it on the dates discussed. Roecker agreed he could not determine the driver’s identity from the Tesla records, but said investigators reached their conclusion (that Burke was allegedly driving) by analyzing the vehicle’s movements alongside the corresponding cellphone data belonging to him.
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Bednarski also pointed out a potential discrepancy between the latitude and longitude coordinates displayed on one of Roecker’s exhibits, which marked where Celeste Rivas Hernandez’s passport was recovered (he noted, however, these weren’t his markings) and the coordinates previously provided in court by California Highway Patrol Officer Sean Buenrostro. Roecker testified that while the numbers were not identical, they were very close and reflected essentially the same location.
The People’s next witness was LAPD criminalist Samantha Tosch, who testified she has worked in the department’s DNA Unit for 18 years analyzing biological evidence such as blood, saliva and semen. Tosch explained the crime lab’s quality control procedures, telling the court that every step of the DNA testing process is documented, evidence is securely maintained and analysts follow standardized protocols throughout an investigation.
Tosch testified that she developed a full DNA profile from a toenail sample collected from Celeste Rivas Hernandez during the medical examination, as well as a reference DNA profile from a cheek swab provided by David Burke. She then compared those reference profiles to biological evidence recovered during the investigation. According to Tosch, multiple bloodstains collected from inside Burke’s Tesla (including stains in the trunk and lower storage compartments) produced single-source female DNA profiles that included Celeste’s DNA. She testified that the statistical analysis showed the DNA profile was 1 septillion times more likely to have originated from Celeste than from an unrelated individual.
Tosch also testified about a bloodstain recovered from a black rubber mat in the garage. Although that sample yielded only a partial DNA profile because less genetic material was available, she said 15 genetic markers were consistent with Celeste’s DNA, making it approximately 20 quadrillion times more likely to have originated from Celeste than from someone else.
Tosch went through additional DNA testing conducted on evidence recovered from Burke’s residence and garage. She testified that bloodstains found on a rowing machine, a charger and a green tarp each produced DNA profiles consistent with Celeste Rivas Hernandez, with the statistical analysis indicating the samples were approximately 1 septillion times more likely to have originated from Celeste than from an unrelated individual.
Of note: DNA recovered from a black trash bag produced a mixed DNA profile from four contributors, including two males, one being Burke (but Celeste was excluded). She went on to testify that bloodstains found on hand wipes produced a single-source female DNA profile consistent with Celeste, excluding Burke as the contributor.
During cross-examination, Berk emphasized the limitations of the DNA evidence presented. She first established that Tosch was not the primary analyst who conducted the DNA testing in the case, but was the technical reviewer for work by another analyst (but indicated she contributed to the report). Tosch also acknowledged that prosecutor Beth Silverman reviewed with her the subjects she would be asked about before her testimony so she could familiarize herself with the reports.
Berk then turned to the science itself, eliciting testimony that while DNA testing can identify whether a person’s genetic material is present, it cannot determine how the DNA was deposited, when it was left behind, or what “activity” caused it to be transferred. Tosch agreed DNA can remain on an item for weeks, months or even years, and that lab testing cannot distinguish between DNA deposited through direct contact and DNA that could be transferred by other means. Berk continued to focus on the fact that DNA testing cannot explain how genetic material came to be on an object. Tosch agreed she could not determine how or when Celeste Rivas Hernandez’s DNA was deposited on the rowing machine, and testified the same applied to the tarp, garage mat and charger. Berk also questioned whether the DNA necessarily originated from blood. Tosch responded that she could not make that determination based on the DNA testing alone, and also acknowledged it was possible the DNA instead came from skin cells.
After the afternoon break, Berk turned back to the trash bags recovered during the investigation. Referring to a second black trash bag containing wipes with brown stains, Berk established that the interior of the bag was not swabbed for DNA. Tosch also confirmed that no DNA from David Burke was identified on that trash bag and reiterated that the DNA recovered from the wipes was consistent with Celeste Rivas Hernandez, while Burke was excluded as the contributor.
Berk revisited the separate trash bag containing a mixed DNA profile, questioning Tosch about the lab’s conclusion that the sample was “consistent with four contributors, at least two males.” Tosch repeatedly testified the mixture was consistent with four contributors. Berk then questioned the use of the “STRmix” software, noting the software generated statistical estimates for each contributor and ultimately excluded Celeste from the mixture. When Berk asked whether David Burke’s inclusion meant he was only a possible contributor (not a definitive one), Tosch ultimately agreed that characterization was “fair.” The attorney also brought up the number of people possibly going in and out of Burke’s garage, and Tosch also stated that characterization was “fair” as well.
During the redirect, Silverman clarified the distinction between what is possible and what is supported by the DNA analysis, citing that a sample would not be reported as matching the victim unless it was consistent with her DNA profile. Tosch agreed, testifying that was correct.
The last witness of the day (who will continue into tomorrow), was Dr. Grant Ho, the deputy medical examiner with the Los Angeles County Medical Examiner’s Office. Ho testified he has worked in the office for five years, has performed 2,500 autopsy examinations and has testified in court roughly 40 times. He told the court he conducted the autopsy on the remains identified through dental records as 14-year-old Celeste Rivas Hernandez. Ho testified that at the time of her death she measured 5 feet 2 inches tall and weighed 71 pounds. He described the remains as “markedly decomposed,” explaining that the condition significantly interfered with the autopsy examination. Ho also observed evidence of trauma to the body consistent with dismemberment of the extremities and noted that Celeste was wearing braces at the time her remains were examined.
Court adjourned at 4 p.m. and will continue Friday at 9:30 a.m.
Lauren Conlin
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