A man charged with trying to blow up a jetliner with explosives hidden in his shoes was still feeling the effects of Valium when he was questioned soon after his arrest, a doctor testified Wednesday.

The testimony came during a hearing on a request from Richard C. Reid's lawyers to throw out a confession he allegedly made to FBI agents

They argue Reid was still under the influence of sedatives he was injected with after being overpowered by crew and passengers aboard the American Airlines flight from Paris to Miami three days before Christmas.

Prosecutors maintain the sedatives had little or no effect on Reid during questioning. Reid, a 28-year-old British citizen, faces eight charges, including attempted murder and attempted destruction of an aircraft.

Testifying for the defense Wednesday, Dr. Mark Dershwitz said the Valium had not worn off by the time Reid was read his rights and questioned, about eight hours after the injection.

Reid may have understood his rights initially, but the drug likely affected his memory later in the questioning, Dershwitz said.

"With the passage of time, his ability to remember the reading of Miranda rights would be gone," said Dershwitz, a clinical anesthesiologist at UMass Memorial Medical Center in Worcester.

Dershwitz said he based his conclusion on witnesses who said Reid had slurred speech and difficulty holding up his head as the start of the interview.

Because the Valium was injected in Reid's abdomen, it would have taken longer to take effect and would have worn off more slowly than if it had been injected intravenously, Dershwitz said.

Reid was injected with 10 milligrams of the drug; the doctor said a normal dose ranges between 2 and 5 milligrams.

On Tuesday, a flight attendant and an FBI agent testifying for the prosecution said Reid appeared alert and responsive throughout the interview.

The hearing was scheduled to resume June 18. Reid's trial is set to begin Nov. 4.

Meantime, French anti-terrorist police took five people into custody Wednesday in connection with the Reid investigation. The suspects are believed to have assisted Reid during his stay in Paris, Le Monde newspaper reported.