By Anita Chang
The Associated Press

COLUMBUS - With every diploma handed out this spring, investigators worry that they might lose information that could tell them who set a rooming house fire that killed five college students a year ago near Ohio State University.

Two of the victims were from the Greater Cincinnati area.

"There's always been a concern about the size of Ohio State, the fact that people come in to Ohio State globally. When they leave, some of the people may never come back to Columbus," said homicide Detective Mike McCann.

"We have been under the gun to get in contact with these people before they leave Columbus."

The April 13 fire started about an hour after the end of a 21st birthday party in a tree-lined student neighborhood just off the main drag of the nation's second-largest campus. Three students were saved by firefighters who had to crawl under dense blankets of smoke. The flames ended up blackening everything but the brick of the yellow three-story house.

About three months later a suspect was arrested on aggravated murder and arson charges. However, prosecutors dropped the charges, saying detectives needed more time to pursue leads and build a stronger case with direct or eyewitness evidence. The evidence could include anyone who may have seen someone preparing to start the fire or overhearing someone talk about setting the fire.

The victims' families echo the concerns of investigators.

"The likelihood of somebody being much younger that knew these kids is more removed," said Patty Dennis, whose daughter, Andrea, died in the fire. Dennis was from Madeira.

"Each year there's less and less people around who were involved and know about it."

Investigators have collected about 100 tips, and a $35,000 reward is being offered for information leading to an arrest and indictment. In hopes of drumming up new leads, Central Ohio Crime Stoppers has put up three billboards near campus and plans to erect two more.

They display a photo collage of the victims and the message: "Last year five students received death by fire. The arsonist received nothing. Who is responsible?"

Franklin County Prosecutor Ron O'Brien said recently that police were still investigating Robert Lucky Patterson, the man arrested and then released, along with others.

Police had said Patterson, 21, had a history of setting fires and was in the area breaking into cars the night of the fire.

One fire investigator said all that's lacking is direct evidence linking him to the fire.

"We feel our suspect is the right person and the issue is they feel they don't have enough evidence to win the case at trial," said Capt. Steve Saltsman who supervises the fire investigations unit.

Patterson's father, Ron, said last year that his son was innocent and was singled out because authorities wanted to close the case.

Robert Patterson could not be reached. He was charged Wednesday with stealing jewelry from a family friend he lived with in November, and a warrant was issued for his arrest.

For the families of the victims, waiting for answers doesn't get any easier.

"It's whole different life without Andrea," Dennis said. "If it's your child and someone you love, you just can't let it rest."

Andrea Dennis, Erin DeMarco and Christine Wilson were students at Ohio University in Athens and were visiting Columbus for the party. Kyle Raulin, of West Chester, and Alan Schlessman lived at the rooming house with 10 other Ohio State students.