What they found has devastated a family and touched people in Sammamish and Seattle, where he and his wife worked.
Dr. Rick Nicolini, his wife and adult son were all found dead inside their home in Sammamish's tony Broadmoore neighborhood.
It is a development where neighbors say they know each other by name.
But few people knew the Nicolinis well.
"They kind of kept to themselves," said neighbor Rick Willard. "I saw the kid when he was going to school."
And Willard said he saw nothing that foreshadowed this.
"And you never heard, you never saw anything between, among them, that would make you say ..." he was asked.
He interrupted the question and said, "Never heard them yelling or screaming. Nothing, yeah. Just heard them doing yard work."
He said the entire neighborhood was surprised to see King County sheriff's deputies surrounding their home Saturday night.
On Monday, investigators said all indications are that Richie Nicolini killed his parents, then took his own life.
Nicolini and his wife, Mary Ellen, worked at his dental office on Olive Way near downtown Seattle.
KIRO-TV went to Sound Dentistry.
"Hi there," said reporter Deborah Horne. "We're from KIRO 7."
But the receptionist said everyone was grieving too much to talk. No patients were waiting; the Nicolinis didn't work Mondays.
Back at their home in Sammamish, a second car was parked in the driveway. The people in it said they had nothing to say. All of this is a sorrowful coda to three lives.
"Yeah, it's sad," said Willard.
"Sad and, as you said, a surprise?" he was asked.
"Yeah," he replied. "I don't know what would drive somebody to do that."
That is what detectives are trying to determine, too: why Richie Nicolini shot his parents and himself in the head.
The case remains an active investigation.