Facing prison for a string of bank robberies, Benjamin Hoskins Paddock beamed cheerfully at a psychiatrist evaluating his fitness to stand trial, and mused at length — at times with “becoming modesty” — about his life stealing cars, running cons, enduring solitary confinement and getting fired from a job as a bus driver after playing tag with the buses.

“I’m a third time loser,” Paddock, the father of the Las Vegas gunman, Stephen Paddock, told the doctor with a smile, according to a summary of the doctor’s evaluation. Though he was in a jail cell in Phoenix, Paddock expressed no regrets, and claimed to have a genius IQ.

“Maybe,” he wondered aloud, “I’m an alert psychotic.”

A few years later, he ended up on the FBI’s most wanted list.

Nearly two weeks after the shooting in Las Vegas, investigators have found few clues to explain why Stephen Paddock amassed an arsenal of assault-style weapons and turned them on concertgoers at a country music festival. FBI profilers are trying to construct a psychological makeup of Paddock, which probably includes the family history of mental illness.

If so, one of the most telling documents might be a yellowed, four-page psychiatric evaluation from 1960 that details the father who raised Stephen Paddock until he was 7 and who loomed over the family even after he disappeared.

When Benjamin Paddock sat for the examination, he was built like a refrigerator and wore a neatly trimmed blond mustache and horn-rimmed glasses that framed strikingly light gray eyes. Pleasant, clean-cut and “incongruously cheerful,” he chain smoked through the interview, offering an gripping biography with a “fluent command of language.”

“He smiles frequently, sometimes winningly, shows occasionally just a touch of ruefulness,” the psychiatrist, William B. McGrath, noted. “No despair, alarm or concern about his fate is manifest.”

“I get the impression he enjoys being an interesting subject of examination,” the doctor wrote. He concluded that Paddock was bright, with no history of “mental defect,” and was able to stand trial. But, the doctor added, Paddock had a “sociopathic personality.”

The portrait of Stephen Paddock that investigators have assembled stands in stark contrast: Reserved, even boring, he was an accountant and investor who liked to gamble only after calculating all the risks. Before the shooting, authorities say, he had never broken the law. Among the many questions that are unanswered is what influence, if any, his father’s absence and infamy had on his life.

In the evaluation, Benjamin Paddock boasted that his run-ins with authority started early and rarely stopped. He was an only child, pampered by his mother and not disciplined by his father. “I got away with an awful lot,” he told his evaluator. “I went where I felt like it, disrupting everybody’s schedule.” By 12, he was driving his own car.

He quit high school almost as soon as he started, then joined the Navy at age 15, but was discharged a few months later, he said, when the Navy figured out “I wasn’t going to do what they wanted me to.”

He drove buses in Los Angeles, but got fired for a game of bus tag with other drivers.

In 1946, he was caught stealing a car in Chicago and reselling it in “a fraudulent fashion.” He spent five years in prison, 70 percent of it, he said, “in the hole,” or solitary confinement, because he was “unable or unwilling to abide by rules.”

When he got out, he made good money selling used cars in Chicago, but quit because, he explained, “the thrill had gone out of it.”

During that time, he got married and fathered Stephen, who was born in 1953. He also set up a fraud ring that he said passed $90,000 in bad checks. He was caught and sent back to prison.

When he was released in 1956, he moved with his wife and son to Tucson, Arizona. The couple had three more sons, and Benjamin Paddock operated a service station, a nightclub and a garbage disposal franchise. He bought a house and a car and got involved in the local hot rod and ham radio clubs.

He also walked into the sheriff’s office and offered to counsel troubled youths.

“I only took the incorrigibles,” he told his evaluator. “I have a knack for social work with kids. I told them I had a degree in social psychology, and nobody bothered to check up on it. They regarded me as a leading light on juvenile delinquency.”

He boasted that none of his charges had ever ended up back in court.

While Stephen Paddock was playing at the family’s white ranch house, his father was robbing banks with a snub-nosed revolver and getting away in the family station wagon. He said the ham radio equipment he kept in the car was ideal for a robber because he could listen in on the police.

Benjamin Paddock was caught in 1960. But the bank robbery charges, he insisted to the psychiatrist, were a case of mistaken identity. A criminal syndicate was forcing him to take the rap.

For years after Paddock was arrested, his sons were told he was dead. Later, they learned the truth, and some visited him, his son Eric Paddock said, but none seemed to form a close relationship. Eric Paddock cursed his father in an interview and said he was angry at him for being more interested in crime than his family.

The authorities have not said what they know about the convict’s relationship with Stephen Paddock.

Facing trial, Benjamin Paddock insisted that he was not crazy. He said he had “never been mental ill, ‘never even unconscious.’” As an aside, he explained that he could get a cushy job in the penitentiary that would beat the boredom of the mental hospital.

In the long account of his life, Paddock never expressed remorse. A few months later, a judge sentenced him to 20 years in a federal prison. He broke out after eight and spent much of the rest of his life on the lam.

© 2017 The New York Times Company