The man identified by California law enforcement officials as the gunman in a mass shooting at a San Jose rail yard on Wednesday lived alone and had a hostile personality, according to interviews with a neighbor and an ex-girlfriend, as well as a review of court records.

The gunman, Samuel James Cassidy, 57, lived southeast of downtown San Jose, in a suburban neighborhood of cul-de-sacs and palm trees, public records show. Doug Suh, a real estate agent who lived across the street, described Cassidy, who authorities say appeared to have killed himself, as someone with a short temper.

“I was afraid of him,” Suh said. “My wife was scared of him, too.”

“He lived alone,” Suh said. “I never saw any friends or family. I never saw anyone else going into the house.”

Suh recalled Cassidy once lashing out at him when Suh turned his car around in Cassidy’s driveway. “He yelled, ‘Do not come onto my driveway.’”

On Wednesday morning at 5:40 a.m., Suh’s security camera captured Cassidy, who was wearing a uniform with reflective stripes, loading his white pickup truck with a black bag. About an hour later, Suh left his house to play golf and saw that Cassidy’s house was on fire. Suh called 911.

Family court records show that Cassidy was married for 10 years before divorcing in 2004. The couple had no children.

In 2009, Cassidy sought a restraining order against his former girlfriend, Jingkun Wang, known as Connie. In court filings, he accused her of vandalizing his roommate’s car, calling at late hours of the night, hurling insults and suggesting she had him under surveillance.

Wang countered that Cassidy, whom she had dated for a year, had “major mood swings due to bipolar disorder” which were exacerbated when he consumed large quantities of alcohol. She also accused him of forcing himself on her sexually.

Their relationship failed when he told her around February 2009 that a female houseguest had moved in, and that she should no longer come visit.

She denied vandalizing any vehicles, and accused him of stealing items from restaurants and employers, and failing to return her television and computer printer.

“He has manipulated me in many ways which are apparent to my friends and family,” she said.

The court ordered Wang to stay at least 300 yards from him, his parents and his new girlfriend for three years.

In a phone interview Wednesday, Wang, now 58, said she had not spoken to Cassidy in 12 years, but described him as someone who was “not mentally stable,” who would be loving one moment and mean the next. She also described his drinking as excessive.

They met on Match.com, Wang said. Two months into their relationship, he told her to pick a diamond ring and he would buy it, she recalled. She declined.

After they broke up, Cassidy showed up at her apartment complex one day, Wang said. A neighbor let him in and he took her brand-new Toyota Camry, for which he had a key, without permission. He returned it damaged from what he told her was an accident, she said.

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