BATON ROUGE, La. -- The boyfriend of a woman whose death has been linked to the south Louisiana serial killer gave details Monday about the circumstances of her abduction and what he has learned since her murder.

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Lee Stanton spoke exclusively to WDSU NewsChannel 6 about the death of his girlfriend, Carrie Yoder. Yoder, 26, a doctoral student at Louisiana State University, disappeared from her home March 3. Her body was found March 13 in Whiskey Bay. She had been strangled to death.

Stanton, who dated Yoder for three years and talked to her every day, reported her missing two days after their last conversation. Stanton said Yoder was on her way to a nearby grocery store when they spoke by telephone.

"She asked if I was coming over for supper," Stanton said. "I said I was going to stay home, and I said, 'if I don't talk to you tonight, I'll talk to you later tommorow.'"

That was Monday. Stanton said Tuesday came and went with no word from Yoder, despite his repeated calls to her home.

"I felt like the hypersensitive boyfriend, you know?" Stanton said. "We've always respected each other's space. Her car was there. The lights were on. I looked through the sliding-glass door the best I could and nothing appeared to be abnormal.

Finally, on Wednesday, Stanton decided to go inside the home.

He said he knew something was wrong when he found Yoder's purse, keys and cell phone on a counter. Stanton then called police.

When detectives arrived, Stanton led them through the home. He said one particular item, a wall-mounted key holder, caught his attention because it was askew, hanging by just one nail.

"It gave every indication that whatever happened to Carrie happened right there at the front door," Stanton said. "That was the only thing out of place."

Stanton said he thinks Yoder's killer came to her door, she opened it, and then was grabbed. Task force detectives seized the front door as evidence in the case.

"Whoever this person is they exude a sense of, 'You can trust me,'" Stanton said. "They exude that comfort. You know, you look through, you see, you identify someone on the other side of the door, and it's like, 'Oh. This is OK for me to open my door for this person.' I'd tell people to ask that question of themselves. Who would you open the door for?"

The LSU professor who introduced Stanton and Yoder, Bill Platt, said he thinks the killer may be dressed as a law enforcement officer. Platt said he also thinks the killer watched Yoder from a warehouse parking lot near her home to learn more about her habits and schedule.

"We found one location where somebody could, if they were parked in this location, could observe her front door, her windows and her parking area of her house," Platt said. This location happens to be at a LSU warehouse that didn't have people around there a lot of the time, and certainly and over the Mardi Gras weekend certainly didn't have people working there."

Platt said women should take a look at where they live, notice spots from which they could be observed, and then keep an eye on who is there.

Platt and Stanton are urging women to take the situation seriously.

"What you think happens to other people -- well, I am other people," Stanton said. "It can happen to you. It can. And I don't want it to happen to anybody else."

Stanton and Platt said detectives eliminated as suspects Yoder's family members and close friends through DNA tests.

Like the other murdered LSU students, a scholarship fund has been set up in Yoder's memory.

Dozens of Baton Rouge-area murders in the past decade remain unsolved. Five of them are connected by DNA one killer: the deaths of Gina Green, Murray Pace, Pam Kinamore, Dene Colomb, and Yoder.

Pace is among three LSU students murdered in the past 18 months. Also killed were Gerilyn Desoto, who was found stabbed to death in her Port Allen home in January 2002, and Christine Moore, who disappeared from her Baton Rouge home in May 2002. Moore's body was found a month later in Iberville Parish.