NASHVILLE, Tenn. -- A man said that if Jerome Barrett is linked or convicted in Marcia Trimble’s death, questions that defy logic will remain.

Former Federal Bureau of Investigation agent Richard Knudson said even if Barrett’s DNA is a perfect match, there are outstanding questions.

According to Channel 4 News, DNA evidence has linked Barrett to Trimble’s death, though he has not been officially charged. Trimble was found dead about a month after disappearing in 1975. She was last seen delivering Girl Scout cookies in her Green Hills neighborhood.

Barrett was recently arrested in connection with the 1975 slaying death of Vanderbilt student Sarah Des Prez. Barrett was arrested in Memphis. He was released from prison in 2002 after serving 26 years for the rape of a Belmont student.

Knudson said even if police solve the Trimble case, they still have a mystery on their hands.

Knudson was the top FBI agent in Nashville at the time of Trimble’s case. He was in charge of the search for her.

After witnesses gave statements, the FBI used stop watches to time the order of the events they said happened while taking Trimble's known path through Green Hills. Knudson said Barrett would have had to come out of nowhere.

“You have people that are coming home from lunch and people walking into their house. A lady gets off the bus and they see the car. And then you see the family putting on the evening meal. … Like I said, we got the stop watches out and we walked and did a computer simulation, that type thing to say, ‘Here’s what, it had to happen right in here,’” he said.

Even if the DNA evidence links Barrett to the slaying, Knudson said the theory that Barrett was guilty still doesn't make sense and that it still doesn't all come together. He said if this is the missing piece of the puzzle, why is it such a difficult fit?

“What are the chances that at that precise moment, he was cutting through that property and here comes Marcia selling Girl Scout cookies, and so then he assaults her. Sure; is it possible? Yeah. Likely? Maybe no. Maybe it is a longshot,” he said.

At the same time, as an FBI agent, Knudson said he believes in DNA and, questions or no question, if this is a perfect match, then the case is closed.

“If there’s DNA there that matches his, I don’t know how you defend that. I mean, is there reasonable explanation? (It would) look to me like they have their man,” he said.

Location Of Slaying Also Questioned

There is another part of the case that Knudson said absolutely mystifies him.

One of the biggest is if Barrett did kill Trimble, did he do it in the same Green Hills garage where she was found or did he kill her somewhere else and move her?

According to investigators, Trimble's body was in the garage for 33 days under a plastic swimming pool.

But human experience doesn't fit that piece of science, investigators said. All the human evidence feels like Trimble was slain somewhere else and moved to the garage, according to those close to the case.

The garage where Trimble was found, which belonged to the Thorpe family, was 50 yards from where she was last seen.

The garage was searched three or four times in the days following her disappearance.

The top canine team in the world was brought in to help in the search. It was the same team who helped locate Patty Hearst.

“He walks right by that garage. Those dogs walked right by that garage,” Knudson said.

The day they found her body, investigators gathered all the recruits who had searched the garage from top to bottom.

“They got the police recruits that were in there and had a young guy who did a sketch. His memory was that good where he was sitting, he remembered the table, the pool and he went around and sketched and he was accurate. He said the body wasn’t there,” Knudson said.

No one thought she was there the whole time except the experts who examined her body.

“The experts say she was, so I’ve got to go with them. Now, we contrast this with the Thorpe family that was out there, they potted plants and whatever. … There were rodent in that garage. Dogs, cats and everything else like that (and) there’s no evidence of the disturbance of the Girl Scout cookie box, much less her, nothing. … It just never made sense to any of us,” Knudson said.