Walnut Creek murder-suicide suspect used “ghost guns,” police say

A 21-year-old Lafayette man who shot his former girlfriend to death at her Walnut Creek home before taking his own life used two untraceable “ghost guns” he built himself with mail-ordered parts, police said Tuesday.

Scott Bertics shot and killed Clare Orton, 19, at her home in Walnut Creek’s North Homestead neighborhood about 6:50 a.m. July 21, said Walnut Creek police Lt. Lanny Edwards.

An investigation determined that Bertics had secretly purchased various parts for the guns by mail and then built the weapons himself, Edwards said.

Police referred to the firearms as “ghost guns” because they contained no serial numbers.

The homemade guns usually include unfinished lower receivers, the critical mechanism from which bullets are fired. Lower receivers normally require serial numbers, but incomplete ones can be bought as just simple pieces of metal.

There was no evidence that the retailers sold Bertics the gun parts illegally, Edwards said.

“There has been nothing in this investigation to suggest anyone else was involved or had any knowledge of Scott Bertics’ plans prior to the tragedy,” Edwards said.

Bertics, who had once dated the victim, was a 2012 graduate of Acalanes High School in Lafayette who went on to Stanford University.

Orton was a 2014 graduate of Las Lomas High School in Walnut Creek, where she was a cross-country and track athlete. She was studying environmental engineering at San Diego State University and made the dean’s list in the fall semester.

Bertics also ran cross-country and track in high school, then studied electrical engineering and computer sciences at Stanford. He took a leave of absence from the university after the fall 2014 semester, officials said.

In September 2014, Gov. Jerry Brown vetoed a bill that would have tightened laws on unregistered guns built with parts purchased online and delivered through the mail.

The bill — proposed by state Sen. Kevin de León, D-Los Angeles — would have banned the sale of gun parts unless they had serial numbers and required buyers to go through background checks.

At the time, De León warned that criminals, gang members and anyone else who wants to avoid background checks can get the parts through the mail and assemble their own guns.

In his veto message, Brown said, “I appreciate the author’s concerns about gun violence, but I can’t see how adding a serial number to a homemade gun would significantly advance public safety.”

Henry K. Lee is a San Francisco Chronicle staff writer. E-mail: hlee@sfchronicle.com Twitter: @henryklee