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Former FBI forensic expert Douglas Deedrick—perhaps best known for his testimony about clothing and carpet fibers in the 1995 murder trial of O.J. Simpson—took the stand Thursday as a key government witness in the case against three Dupont Circle housemates accused of covering up the 2006 murder of D.C. attorney Robert Wone.

But his testimony stalled out before it even began, as defense attorney David Schertler immediately challenged Deedrick’s qualifications, as well as the area of forensic science upon which his supposed expert opinion in the case would be based.

Schertler pointed to a report by the National Academy of Sciences, challenging the soundness of “fabric imprint identification” methods, citing a lack of standardized protocols.

Deedrick defended the practice: “Fabric is so versatile it would be difficult to build in a standard,” he said.

Deedrick, now an independent consultant who worked for the FBI from 1972 until 2004, followed by a stint in the D.C. Metropolitan Police Department’s crime lab, has worked on close to 6,000 cases, he said. But can recollect only two, including the Simpson trial, that involved fabric imprint identification.

Schertler questioned whether Deedrick was even officially qualified to testify in the Simpson case 15 years ago.

“Were you formally qualified by the court in the O.J. Simpson case?” he asked.

Deedrick said he didn’t know.

“So you don’t remember if Judge Ito qualified you?” Schertler continued.

“No, I don’t,” Deedrick said.

Schertler also pointed to Deedrick’s testimony in another case, involving the murder of a Columbia University student, in which the supposed expert had misidentified the victim on the stand.

Judge Lynn Leibovitz indicated she was leaning toward letting Deedrick’s testimony proceed. First, she said she wanted to read the Academy of Sciences report.