PORTLAND — After a three-year search for William Greenwood’s killer, a Portland police detective says one new piece of information may be all he needs to solve the case.

Detective Daniel Young also thinks there is someone out there who can provide that tip or fresh lead that will end his years of searching and provide solace to Greenwood’s family.

Greenwood spent his last night at two Portland Street bars, Bubba’s and Rickey’s, where he was hanging out until closing time. He was found shot to death the next afternoon, April 30, 1995, behind a trucking company a few miles away.

Young is sure someone saw or heard something the night Billy Greenwood died and is holding back information.

“It was a Saturday night on Portland Street. Seventy-five people were dumping out of the bars. There’s no way no one saw him leaving,” Young said.

“We feel confident we know what happened. But, we want help from the public. People think we’ve forgotten about this, but we haven’t.”

Young has notebooks filled with interviews and information chronicling all but the last moments of Greenwood’s life.

He has traveled to Oklahoma City, New Hampshire and northern Maine to verify alibis. He has interviewed more than 100 people. He has collected scraps and bits of evidence that, with ever-improving technology, could pinpoint a killer.

“I never thought it was going to be as difficult as it’s been,” Young said. “We found some people he owed money to; we found some people he had words with some time ago, but nothing stood out.”

Young suspects he has already spoken to the killer, or someone else directly connected with Greenwood’s death. But he needs a link, a shred of new information that will stitch one of his theories to the existing evidence and put this case to rest.

Finding the killer would help ease the anguish of Greenwood’s parents, Mildred and Lynwood Stubbs, who find themselves unable to get over the loss of their son and get on with their lives.

“I don’t even feel like I have a life,” Millie Stubbs said. “It’s just empty. People say time heals, but it doesn’t. It gets worse. There are times when I get in the car and I don’t even remember I am going to work. It’s just blank.”

The Stubbs family is offering a reward of up to $5,000 for any new information leading to the arrest and conviction of the person or persons responsible for Greenwood’s death.

Stubbs and his wife keep in contact with Young. They say he is fighting to help them as the rest of the world tells them to move on.

“He’s the greatest. He broke his hump for us and he’s never once tried to discourage us,” Lynwood Stubbs said. “I’ve always had the idea, if anyone is going to do it [solve the case], Dan is going to do it.”