Trying to piece together the story of Richard Bernard Bisbee, homicide detectives came across a letter that could offer insight into why the 68-year-old man apparently snapped Sunday night.

The letter, given to authorities by a friend of Bisbee's, indicated that Bisbee felt he was losing control of his life, that he had nobody to talk to and had contemplated suicide, said Sacramento County sheriff's homicide Sgt. Jim Barnes.

It was a major clue that Bisbee's alleged shooting of a California Highway Patrol officer, which ended in his own death, might have been borne of crisis.

"It looks like there might have been some sort of emotional breakdown," Barnes told reporters Monday afternoon. "His life was starting to unfold and he didn't know how to get out of it."

On Monday, Sacramento County sheriff's detectives pulled at the threads of what they believe was Bisbee's unraveling life.

The prior evening, Bisbee was driving southbound on Highway 99 in Elk Grove when a CHP officer pulled him over, according to authorities.

CHP Valley Division Chief Steve Lerwill said the car's windows were tinted and plastic covered the license plate, making it hard to read. Both are vehicle code violations, Lerwill said.

The officer approached Bisbee's car and spoke to him. When Bisbee allegedly became uncooperative and refused to step out of the car, the officer radioed for backup, Lerwill said.

A second officer arrived, and the two again approached Bisbee's car. Asked whether he had any weapons in the car, Bisbee said no, but then pulled out a handgun and fired at the backup officer twice, Lerwill said.

As Bisbee fled, the first officer fired at the car. Barnes said it was not yet clear whether that officer struck Bisbee, but said it could explain why he soon lost control of his car, rolling it until it came to a rest on its side.

At that point, other CHP officers and Elk Grove police officers had arrived and surrounded the wreckage. Barnes said the handgun was visible to officers and that Bisbee appeared to be reaching for it, despite orders from officers to stop and show his hands.

Ultimately, an Elk Grove officer fired into the car. The officers retreated and waited for paramedics, who pronounced Bisbee dead at the scene.

Meanwhile, an off-duty registered nurse scaled a wall by the freeway and rendered aid to the injured CHP officer. He underwent surgery that night and is expected to make a full recovery, Lerwill said.

As is standard procedure, the CHP officer and Elk Grove police officer who fired their weapons have been placed on administrative leave until the investigation is complete.

On Monday, detectives were still trying to understand what would have prompted such behavior by Bisbee.

Barnes said he didn't appear to be close to his family. He lived alone in a worn-out trailer on a rural stretch of Bruceville Road, and according to friends, largely kept to himself. He struggled with relationship problems, though Barnes did not elaborate.

Bisbee's younger son, Gary, said he was at a loss in trying to understand news of his father's death. On Monday, he was making plans to fly to Sacramento from his home in rural North Carolina.

"He was a good guy. He wasn't a troubled person," Gary Bisbee, 45, said of his father. "He stayed to hisself more – he worked a good, honest life."

Gary Bisbee said he spoke to his father a few months ago and detected no signs of depression. They talked about Gary's three kids, and the elder Bisbee was "laughing, cuttin' a fool, … happy-go-lucky."

Originally from Detroit, Richard Bisbee spent much of his life as a truck driver. More recently, his son said, he had done some work as a private investigator.

He had another adult son in North Carolina, a daughter in Chattanooga, Tenn., and several grandchildren and great-grandchildren.

According to the state Bureau of Security and Investigative Services, Bisbee was licensed as a security guard and held state-issued permits for carrying a firearm and a baton on duty.

To obtain such licenses, Bisbee would have undergone criminal background checks by the state Department of Justice and Federal Bureau of Investigation, according to BSIS records available online.

He again underwent a background check when he applied for, and was granted, a concealed weapons permit in Sacramento County in May 2010.

Upon hearing after the shooting that Bisbee had a permit, Sacramento Sheriff Scott Jones said he immediately assigned detectives to pore over Bisbee's file looking for red flags that should have held up his application. They found none, Jones said.

Bisbee's application, which Jones released to reporters, indicated he previously had been issued concealed weapons permits in Calaveras and Amador counties, but that the permits had expired.

Bisbee sought the permit for a Sig Sauer P239 9 mm handgun. However, Jones noted that was not the gun Bisbee allegedly used to shoot the CHP officer Sunday night.

In an attachment to the application, Bisbee wrote that he used to work for a private investigator in Amador County, serving summonses and doing surveillance.

"I would like to get back into the field again," he wrote. The permit would be helpful, he said, because "I get sent to places nobody else wants to go."

Barnes noted the incident has been emotional for the community, for law enforcement and for Bisbee's family, and said detectives will continue looking for answers to bring some closure.

Until then, Gary Bisbee will struggle to make sense of it.

"There had to be a reason," he said. "He wouldn't just open fire on a police officer for no reason. He's never harmed anyone."

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