Police said Tersargyan was arrested Wednesday night at his Hollywood-area home and a weapon was found. He was booked on suspicion of killing 38-year-old Karine Hakobyan, whose body was found slumped in the driver's seat of her Honda CRV on March 26.
Hakobyan had returned home and parked her car in a carport at her apartment complex on the 5800 block of Lexington Avenue at about 8:20 p.m. when she was shot in the head.
Tersargyan was allegedly obsessed with Hakobyan and had been stalking her, according to authorities and a close family friend. He was allegedly waiting for her to return home the night she was killed.
Tersargyan made a brief appearance at the downtown Los Angeles courthouse in connection with the shooting death of Hakobyan, but his arraignment was postponed until May 6. He was ordered to remain jailed without bail.
Court records list Tersargyan as 73 years old, but police officials said he may be in his late 50s.
Police said Tersargyan was investigated as a possible suspect in the December 2008 shooting deaths of the woman's husband, 43-year-old Khachik Safaryan, and their 8-year-old daughter Lusine.
Their bodies were found in their home on the 1200 block of Tamarind Avenue by the couple's then-12-year-old daughter when she came home from school. They had been shot in the head.
Last month, that same daughter also discovered the body of her slain mother.
She recounted the horrifying experience of discovering her parents and little sister in a letter she was planning to send to President Barack Obama.
She says she is tortured by the images in her mind of having the found of the three family members. She says the things she's seen at her age, others would never she in a lifetime.
The devastating discovery of her father and sister in 2008 and the months of turmoil that followed prompted the girl to write the letter to President Obama, asking for help bringing her aunt over from Armenia.
"Our family is falling apart now. My grandparents are sick and depressed. My mother cannot cope with the loss of her husband and daughter. I am not in any better shape: I still see the bloody bodies of my sister and my father as I found them that day," the young girl wrote in the letter.
Then after she found her mother's body, she added a P.S. to the letter, talking about the moment she realized her mother had been murdered.
"When I arrive in front of my mom's wide open car door I see blood. Slowly, I feel the world tear down in front of my eyes. Every second thousands of things cross my mind. I get closer, panicking, shaking my mom twice, running to get help, yelling," she wrote.
The teenager says that words can't describe how she feels. She says everything still feels like a nightmare and nothing seems real.
The letter has yet to be sent to President Obama.
City News Service contributed to this report.