KIRKLAND, Wash. -- A widow wants to know: who killed her husband?

It's been seven years since Mike Emert was murdered. Mary Beth Emert has lived those years with the pain and the questions.

Her husband's killer did leave behind clues, but those clues have only baffled investigators and given her grief.

On January 4, 2001, Mike, who was a realtor, was showing a home in Woodinville to an older man he knew only as "Steven." The man limped, carried a cane and made Mike uneasy.

"I just remember him standing in the kitchen, you know, saying the guy was a little odd," said Mary Beth.

Investigators believe Mike picked up Steven in Kirkland in his Cadillac SUV, then drove to the house. That's where detectives found Mike upstairs.

"It was a pretty horrific scene," said King County Sgt. John Urquhart.

Mike had been stabbed some 20 times. The fatal wounds showed he'd tried to defend himself.

"This is a tough one," Urquhart said.

There was no other woman, no history of drugs or gambling. Mary Beth wonders if it was a business dealing.

"He had a few interesting people along the way, and a few interesting transactions at that," she said.

Investigators have not found any enemies that wanted Mike dead. And the killer's trail is cold. He had covered his tracks by dragging Mike's body into the bathroom.

"He was in the tub, so I think that washed away any evidence on his body," said Mary Beth.

The only things that were missing were Mike's watch and wedding ring. With so little to go on, some believe Mike's death was the work of a hit man.

"If they weren't professional, how could they get away so clean?" Mary Beth said.

Days after the murder, investigators thought they had tracked down the mystery man, Steven. He was in his 60s and walked with a limp, but had an alibi.

"Couldn't even raise him to the level of a suspect, but we couldn't totally clear him 100 percent," said Urquhart.

He has since died, but detectives are still pursuing leads they developed after talking to him.

And seven years later, Mike's murder remains an active investigation.

"It's really unimaginable to think that somebody could do this without a trace," said Mary Beth.

Detectives believe someone saw the killer drop off Mike's SUV at a Kirkland parking lot after the murder. A $50,000 reward is being offered in the case.