RADFORD -- A man expected to be a key defense witness may have ended up aiding the prosecution in its case against photographer Bob Shell on Tuesday, the sixth -- and possibly next to last -- day of testimony in the trial.

Chuck Westfall, Canon camera's director of media and consumer relations, was on the witness stand for just more than 90 minutes testifying about the technical workings of the Canon EOS 10D, the digital camera Shell used to shoot hundreds of photos on June 3, 2003.

Shell is charged with felony homicide, defiling a corpse, and several sex and drug charges in connection with the death that day of 19-year-old model Marion Franklin.

Using a computer and software he brought with him, Westfall analyzed the microdrive seized by police as part of the investigation.

At first, he said data indicated the last picture on the microdrive was taken at 5:31 p.m. After looking further into the data, though, Westfall said the last picture, a photo of Shell touching Franklin, was stamped 6:53 p.m. -- the time the prosecution has relied on but the defense has disputed.

Commonwealth's Attorney Chris Rehak has said Shell accidentally killed Franklin by giving her morphine, then touched and had sex with her after she had died.

The time of the last photo is important because Shell called 911 at 7:03 p.m. that night, and rescue workers have testified that Franklin was cool to the touch when they arrived at Shell's studio at 239 West Main St. minutes later.

When it was seized by police, the clock on Shell's camera was within a minute of the atomic clock, according to earlier testimony in the trial.

Westfall also provided possible explanations for a Dec. 31, 1979, stamp on one photo of Franklin and for varying time stamps on several sets of copies of photos. It's not uncommon for a computer to assign that December stamp to a file that doesn't have a creation date, he said, and sometimes a computer will change the hour -- but not the minutes -- assigned to a set of photos.

Copies of photos in files from Shell's microdrive show the same last photo taken at 2:53 and 3:53 as well as 6:53 p.m.

Shell's computers were also the subject of debate Tuesday. Radford police seized one from Shell's studio, one from his home and one from Franklin's apartment.

Instead of sending them directly to Virginia State Police to be analyzed, as a state police special agent testified they should have done, Radford police searched them for evidence.

State police finally received the computers on Jan. 30, 2004, and carefully made copies of the hard drives, not knowing the computers had been operated for months.

Former Macintosh consultant Steve Ayers testified Tuesday that he inspected the three hard drives to see if any changes had been made while in the custody of the Radford Police Department.

"All three of the hard drives had been edited in some fashion," he said. He couldn't say, though, what had been altered or how.

Also during testimony Monday and Tuesday, defense attorney Jonathon Venzie called six witnesses who testified about Shell's reputation as a photographer.

Each said Shell is known for the professional way he treats his models.

"He was regarded as one of the photographers you could trust your wife or daughter with," said Charles Whitescarver, a photographer and associate director at Virginia Tech's Volume Two Bookstore.

John Richards, a photographer and computer programmer for the federal government, said he has participated in at least half a dozen of Shell's photography workshops over the years.

At one, he said, Franklin was one of the models. She encouraged photographers to take explicit photos of her, he said.

"She was willing to do poses I wasn't willing to shoot," he said.

Court recessed early Tuesday because the case was ahead of schedule and none of the defense's remaining witnesses was available.

Venzie plans to call at least five more witnesses, but refused to say if Shell will take the stand.

Venzie had planned to take jurors on a tour of Shell's studio, but Circuit Judge Joey Showalter denied his request.