Former Stanford engineering student Scott Bertics used a gun he constructed himself to kill his ex-girlfriend Clare Orton and then himself. Police are still searching for a motive for the murder-suicide of the couple, who had not been romantically involved since 2013.

According to a San Jose Mercury News article, the two guns from the crime scene lacked serial numbers, and a police investigation revealed that Bertics had assembled the guns himself by ordering parts from online manufacturers.

Though Bertics’ purchased and assembled the weapons legally, Walnut Creek Police Lieutenant Lanny Edwards noted that building them is no easy feat. The young student “had to know what he was doing,” Edwards told the Mercury.

The shooting has raised serious questions about homemade “ghost guns,” which are difficult to trace and control.

Police have not yet found a motive for the murder-suicide, and officials stated there were no “red flags” that foreshadowed Bertics’ violent actions. Currently no evidence indicates that Bertics involved other individuals in the crime or notified others of his plan.

The Las Lomas community held a candlelight vigil for Orton on July 27 to express its grievances and show support for her family.

Contact Lea Sparkman at 16lsparkman ‘at’ castilleja.org.