A Case of Incompetent DNA Evidence Processing
The DNA Evidence
After Tiffany was sexually assaulted, Dr. Hildebrant gassed her unconscious. She then woke up with extreme pain in her anus, in the care of a female nurse. After she woke up, Tiffany was in a state of emotional shock. When she went to the bathroom at the hospital, she pushed a significant amount of milky-looking, bloody fluid out of her anus to see if there was semen inside of her. Unfortunately, in her shock, Tiffany was not thinking about the importance of the preservation of DNA evidence at that moment.
Tiffany received a rape kit exam in a timely manner the day after her assault.
Even when a victim pushes out most semen about 1 hour after ejaculation, an internal anal swab collected about 24 hours after an assault would, if tested in a timely manner, be expected to recover substantially more than trace amounts of male DNA/sperm — typically an amount in the nanogram range and enough for a full or a partial male DNA profile with a high statistical weight.
However, when Tiffany was sexually assaulted by Dr. Hildebrant, Oregon had a significant rape kit backlog. Hundreds and hundreds of rape kits were sitting on shelves, waiting long periods of time to be tested. The rape kit backlog, which is a problem in many states, has significant consequences for victims and public safety. As rape kits sit on shelves, DNA degrades.
The Oregon police can “rush” rape kits when there is a public safety risk. Even though Dr. Hildebrant was a public safety risk, Detective Megan Townsend did not designate Tiffany’s rape kit as a “rush” case until March 2024, about 8 months after her sexual assault.
There was a 7–8 month gap between the collection and testing of the swabs in Tiffany’s case. The laboratory information management system's chain of custody report confirms the swabs were not extracted until about February to March 2024. The evidence (exhibit 1.6) that produced the offender DNA profile for the case was collected from the rape kit in March 2024.
Studies on long-term storage of dried swabs/swab extracts demonstrate minimal DNA degradation over time for high-quantity DNA samples (such as internal samples of un-expelled semen), but in ultra-trace scenarios (such as internal samples of residual semen after a victim has pushed out most semen), the effective DNA yield drops sharply. Trace/low-template DNA samples (such as samples of residual semen in an anus after semen expulsion) routinely degrade to the picogram range or become undetectable after 6–12 months. After 6–8 months, low DNA amount-input anal swabs often result in partial male DNA profiles or no male DNA profile at all.
Such degradation occurred in Tiffany’s case. After 8 months, recoverable male DNA on the swabs was significantly reduced due to gradual degradation, even with proper drying of the swabs and frozen storage. Extracts showed only trace male DNA and a limited male DNA profile. The long storage delay before testing and the initial low DNA deposit on the swabs (since Tiffany pushed out the semen) explain the trace results. The trace DNA results in Tiffany’s case are consistent with published forensic persistence data and long-term storage studies.
National and international guidelines (NIJ National Best Practices for Sexual Assault Kits, OSAC standards, SWGDAM recommendations, and multiple peer-reviewed studies) all specify that people should use firm pressure while rotating or rolling swab heads across a surface while collecting DNA to dislodge sufficient cells from the skin or mucosal surface. Firm pressure + rotation is explicitly recommended because it dramatically improves DNA yield compared to light touching. However, as explained on this page, the RSI nurse who collected Tiffany’s swabs, and unbeknownst to Tiffany, was performing a “rapid” version of a rape kit exam, used extremely gentle, feather light-like swabbing. Extremely gentle/feather-light swabbing is a known cause of poor DNA recovery in sexual assault kits and is not recommended by any forensic authority. “Feather-light” or extremely gentle swabbing fails to dislodge sufficient cells from the skin or mucosal surface. Multiple studies show that light swabbing recovers significantly less DNA — often 50–90 % lower yields — than moderate-to-firm pressure with rotation. In low-template scenarios (such as swabbing areas of external sexual contact, or swabbing internal residue after semen expulsion), feather-light swabbing is one of the most common reasons for trace or negative DNA results. The nurse’s extremely gentle, feather-light swabbing on the external anal rim was almost certainly a major contributor to the trace-only male DNA results in Tiffany’s case.
At picogram levels of input DNA, forensic labs get random amplification of any trace contaminant or residual single-stranded DNA. In other words, at picogram levels of input DNA, it may be difficult or impossible to differentiate offender DNA from contaminants, and forensic labs may generate a male DNA profile from swabs containing the offender’s DNA that do not match the offender’s DNA profile. The extremely degraded offender DNA profile for Tiffany’s case did not match the DNA profile for the victim’s boyfriend or Dr. Hildebrant.
As shown in this police report, when Tiffany was notified that Dr. Hildebrant’s DNA did not match the DNA in her rape kit, she was insistent that Dr. Hildebrant raped her. The fact that the DNA didn’t match perplexed Tiffany, who wasn’t an expert in DNA. In preparation for the gynecological surgery Tiffany underwent at OHSU Hillsboro Medical Center, Tiffany took a thorough shower the night before the day of surgery (paying special attention to cleaning her nether regions), slept on clean sheets, and took another thorough shower the morning of surgery, and did not have consensual physical contact with any men between the time of that first shower and the time of her rape kit exam.
Even as law enforcement investigated other staff at Tuality Healthcare as potential suspects, Tiffany always maintained that Defendant Nathan Hildebrant was the sole person who sexually assaulted her at OHSU Hillsboro Medical Center.
When Tiffany hired a forensic scientist to review forensic records for her case, she learned that her case was compromised by the rape kit backlog.
“The fact that the Oregon state government excluded Dr. Hildebrant as a suspect because an extremely degraded DNA sample didn’t match his DNA profile reflects the troubling fact that people in power in the Oregon State criminal justice system have fundamental misunderstandings of the significance of DNA evidence.”
“I did everything I could to protect other women from my offender, but because of the rape kit backlog, everything wasn’t enough.”
“When the government fails to properly process DNA evidence, and then incorrectly tells a victim that the DNA evidence proves that their alleged offender did not assault them, that is like a form of gaslighting.”
The Oregon Medical Board Investigation
On October 24, 2024, the Oregon Medical Board (OMB) first contacted Tiffany regarding her sexual assault allegation. During the phone call, an OMB investigator told her that the OMB was ready to start investigating her alleged sexual assault, because Hillsboro Police Department detective Megan Townsend had recently given the OMB investigator permission to contact Tiffany for the first time. The OMB investigator told Tiffany that the OMB first learned of her sexual assault allegation in late 2023, when a person, deemed anonymous, reported the allegation. In other words, Detective Megan Townsend told the Oregon Medical Board to not contact Tiffany for about a year. After the call, the OMB investigator sent an email to Tiffany thanking her for her time.
On December 5, 2024, shortly after the Oregon Medical Board began their investigation of Dr. Hildebrant, law enforcement declared that Dr. Hildebrant was innocent because the DNA profile in his cheek swab didn’t match the extremely degraded DNA in Tiffany’s rape kit.
When Tiffany subpoenaed records, she learned that, on October 23, 2024, 1 day before she was first contacted by the OMB investigator, evidence (item 5-5.01 in the laboratory information management system’s chain of custody report) from Dr. Hildebrant's cheek swab was transferred within a Forensic Services Division lab for male DNA profile extract referral so that his DNA profile could be compared to the male DNA profile developed from Tiffany’s tampered rape kit. In other words, the time that Hillsboro Police Department detective Megan Townsend first gave an OMB investigator permission to contact the victim coincided with the time that the forensic lab began extracting Dr. Hildebrant’s DNA profile so that his DNA profile could be compared with the DNA profile generated from Tiffany’s rape kit.
“I don’t think there’s any way a police detective could justify ordering a medical board to not investigate a doctor for about a year when that doctor has allegedly drugged and raped a patient. My allegations indicated that Dr. Hildebrant may be a life-threatening risk to other patients.”