BLOOMINGTON, Ind. -- FBI agents believe they're closer to solving the disappearance of Indiana University student Jill Behrman.

The 19-year-old Indiana University freshman disappeared while riding her bicycle the morning of May 31, 2000. She has not been seen since. Investigators have not made any arrests.

Agents held a news conference Friday to announce they're looking for two vehicles related to the case, RTV6 reported.

Investigators said they're looking for a late-model, light color or white two-door convertible driven by a white male in his late teens or early 20s. The male may have transported a female escort-service employee to a job in Bloomington on the night before Behrman's disappearance, investigators said.

Investigators also are looking for a late-model, light color, four-door sedan that may have had a toy troll with green hair hanging from the rear-view mirror. Investigators believe this car had two men and two women inside.

Agents said they believe the people who were either riding in those cars or driving them on the night before Behrman's disappearance may know something vital to the case.

Investigators have already been looking fro a pickup truck believed to have hit Behrman.

Investigators believe whoever struck Behrman moved her body to hide what happened.

Southern Monroe County's Salt Creek has been searched for clues. Investigators say they believe Behrman's body is somewhere in the murky creek.

Behrman's parents, who attended the news conference, said they were encouraged by the recent developments.

"Over all of these months, we've been fairly well-informed of what's going on with the investigation," said Behrman's mother, Marilyn Behrman. "At this point in time, there are a lot more pieces of the puzzle that seem to be coming together."