David Stodden showed up at the Snohomish County Sheriff's Office Wednesday, 12 years after the unsolved murders of his wife and daughter.

"They asked if I killed my wife and daughter, was I involved in the murder of my wife and daughter, did I help plan the murders of my wife and daughter," said Stoddard. "It's kind of insulting to have someone want you to take a polygraph when it's your own family."

Stodden's wife Mary and daughter Susanna were found shot to death along the remote Pinnacle Lake Trail near Verlot in 2006. Since then, detectives have turned up very little in the investigation. It was officially dubbed a “cold case” a year ago when the lead investigator retired.

Wednesday was the third time Stodden underwent a polygraph test. The first two tests were ruled "inconclusive." Stodden said he agreed to a third polygraph out of frustration with the lack of progress.

"I think they were waiting for me to do this before they started working on the case again," he said. "The two detectives I was talking to today have never been to the crime scene. How do you solve a crime if you don't go to the crime scene?"

Extended: David Stodden talks about taking 3rd polygraph test in cold-case murders of his wife and daughter

Stodden has received several anonymous tips over the past few years but those people have been unwilling to talk to police.

"We need someone to come forward with information," he said. "Maybe those people would contact me or the sheriff's office again."

After three hours with detectives, a department spokeswoman announced Stodden passed the polygraph, and he is not a suspect.

But the truth remains elusive.

Stodden is losing hope the killer will ever be caught.

He choked back tears outside the sheriff's office Wednesday, "I'll just say that I still think about them many, many times every day."

Anyone with information on the killings should call the Snohomish County Sheriff's Office at 425-388-3845. A $1,000 reward is being offered and you can remain anonymous.