Judge hints some evidence in ‘Potomac River Rapist’ case may not be admissible

After two days of hearings in September, lawyers in the D.C. case against the man police have called the “Potomac River Rapist” argued over how the evidence was collected, and whether it should be admissible in court when the case goes to trial next month.

While no final decisions were made, the D.C. Superior Court judge expressed some doubts and concerns about some of the evidence collected, the strongest of which was DNA evidence police gathered when they visited the South Carolina home of Giles Warrick in 2019.

Warrick is the man accused of raping and killing a woman in Georgetown more than 20 years ago. Separately, Warrick is also charged with six rapes in Montgomery County.

Warrick’s attorney Stephen Mercer argued that the DNA sample police obtained was coerced.

Mercer referred to transcripts and interviews suggesting that the three officers who showed up at Warrick’s home — detectives from Horry County, South Carolina, D.C. and Montgomery County, Maryland — misled Warrick with words that may have suggested that anything he provided was voluntary. However, the detectives’ body language and methods left doubts, according to Mercer’s argument.



“They gain entry by saying, ‘We’re going to tell you everything that is going on.’ And then they sit down, and then they begin to question him” instead, Mercer argued, describing the words police used after Warrick first answered the door.

He brought up the discussion the detectives had with Warrick. At one point, they mentioned collecting DNA samples to eliminate people from a family tree, even though detectives already believed that Warrick was their man.

However, Mercer’s effort to convince Judge Milton Lee that what happened constituted deception, which should negate the DNA evidence, appeared to fall short.

“I can just tell you right out front, I’m not with you,” said Lee, adding that the totality of the words coming from detectives needed to be considered.

But it was not all lost for Mercer. A second argument involved a previous filing on evidence collected by police on the morning of Warrick’s arrest, less than 24 hours after his first interview with detectives.

By then, the DNA evidence had confirmed a match. In a hearing in September, police admitted that they moved in to arrest Warrick earlier than anticipated when they realized he was awake in the middle of the night and moving around the house.

After the arrest, police searched the home and found a handgun that belonged to Warrick’s fiancee had been moved from the bedroom and found inside a kitchen cabinet. He had been seen moving around in the kitchen when police knocked on his door in the 2 a.m. hour to make the arrest.

Police also later found a series of checks and goodbye letters to both his fiancee and his children.

In a previous hearing, a different judge had called that “consciousness of guilt.” But that evidence may not be admissible.

The judge expressed concern that the search warrant used to look around the house may have been too broadly written, at least in terms of what’s allowable under D.C. law. One example points to a section allowing Warrick’s fiancee to be searched even though there was no evidence that she knew about the crimes in which Warrick was suspected.

“What’s the basis for that?” Lee said. “When you include language about an individual that seems wholly unrelated to the event, it raises a significant question about the breadth of the entire document.”

Lee, the judge, also wondered about a digital camera and other electrical devices that were also listed in the warrant.

Assistant U.S. Attorney Sharon Donovan argued that Warrick’s phone was the only device that was searched; however, it was clear Lee viewed that as more reasons to be leery about the scope of the warrant.

“Let me say this to you,” said Lee, “you got some work to do on this one. I don’t know that you survived it.”

There will be briefings to come in the next few weeks on the matter. The case is set for trial after Thanksgiving, and the judge scheduled another hearing for early November, where he is expected to rule on the issues.

The judge may also decide whether or not the prosecution will be allowed to tell jurors about the series of other rapes Warrick is accused of in Montgomery County.

John Domen

John started working at WTOP in 2016 after having grown up in Maryland listening to the station as a child. While he got his on-air start at small stations in Pennsylvania and Delaware, he's spent most of his career in the D.C. area, having been heard on several local stations before coming to WTOP.

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