Stephen Paddock, the gunman who killed at least 50 people and wounded more than 400 when he unleashed a shower of bullets from a hotel room balcony on a music festival in Las Vegas on Monday, is not connected to any militant group and likely acted alone, Clark County Sherrif Joseph Lombardo told reporters on Monday.

The Islamic State group claimed responsibility for the shooting. Without mentioning Paddock by name, ISIS said he had converted to Islam a few months ago. The FBI however said the Las Vegas shooter had no connection to the international terrorist group.

Paddock, 64, is believed to have checked into the hotel room at the Mandalay Bay Hotel and Casino last Thursday. Ten rifles were found in his room, which he shared with Marilou Danley, a 62-year-old woman who was initially regarded by authorities as related to the case.

An unidentified source in the Clarke Counnty Sheriff's office told the Associated Press that Paddock's foreign travel has become part of the ongoing search for a motive for the mass shooting. Authorities have learned that Paddock took some 20 cruises, many of them in Europe and the Middle East.

The cruises included stops at ports in Spain, Italy, Greece, Jordan and the United Arab Emirates, according to information provided by a law enforcement source, reported CNN.

After carrying out the attack from his 32nd floor balcony, Paddock, a Nevada resident who is said to have lived in a retirement community surrounding a golf course, shot himself before security forces were able to apprehend him. Earlier reports had falsely stated that Paddock had been shot by police.

Paddock’s motive for carrying out the mass shooting, the deadliest in modern U.S. history, remains a mystery and Lombardo said he believes it may have been a “lone wolf” attack. “We have no idea what his belief system was,” he said.

Paddock had a penchant for guns, high-limit video poker and real estate deals. His father was a notorious fugitive bank robber. He had a recent live-in girlfriend, two ex-wives and seemed to live a comfortable life in a Nevada retirement community.

On the surface, Paddock didn’t seem like a typical mass murderer, said Clint Van Zandt, a former FBI hostage negotiator and supervisor in the bureau’s behavioral science unit. Paddock is much older than the typical shooter and was not known to be suffering from mental illness.

“My challenge is, I don’t see any of the classic indicators, so far, that would suggest, ’OK, he’s on the road either to suicide or homicide or both,” Van Zandt said.

Nevertheless, his actions suggest that he had planned the attacks for at least a period of days.

Some of the rifles had scopes, the sheriff said. And authorities found two gun stocks that could have let him modify weapons to make them fully automatic, according to two U.S. officials briefed by law enforcement who spoke on condition of anonymity because the investigation is still unfolding.

“He knew what he wanted to do. He knew how he was going to do it, and it doesn’t seem like he had any kind of escape plan at all,” Van Zandt said.

Son of a notorious bank robber, twice divorced

Eric Paddock also told The Associated Press that he had not talked to his brother in six months and last heard from him when Stephen checked in briefly by text message after Hurricane Irma. Their mother spoke with him about two weeks ago, and when he found out recently that she needed a walker, he sent her one, Eric Paddock said.

Eric Paddock recalled receiving a recent text from his brother showing “a picture that he won $40,000 on a slot machine. But that’s the way he played.”

He described his brother as a multimillionaire and said they had business dealings and owned property together. He said he was not aware that his brother had gambling debts.

“He had substantial wealth. He’d tell me when he’d win. He’d grouse when he’d lost. He never said he’d lost $4 million or something. I think he would have told me.”

Heavily armed police searched Paddock’s home Monday in Mesquite, about 80 miles northeast of Las Vegas near the Arizona border, looking for clues. Paddock lived there with his 62-year-old girlfriend, who authorities said was out of the country when the shooting happened. Eric Paddock described her as kindly and said she sometimes sent cookies to his mother.

Police also searched a two-bedroom home Paddock owned in a retirement community in Reno, 500 miles from Mesquite.

While Stephen Paddock appeared to have no criminal history, his father was a notorious bank robber, Eric Paddock said. Benjamin Hoskins Paddock tried to run down an FBI agent with his car in Las Vegas in 1960 and wound up on the agency’s most wanted list after escaping from a federal prison in Texas in 1968, when Stephen Paddock was a teen.

The oldest of four children, Paddock was 7 when his father was arrested for the robberies. A neighbor, Eva Price, took him swimming while FBI agents searched the family home.

She told the Tucson Citizen at the time: “We’re trying to keep Steve from knowing his father is held as a bank robber. I hardly know the family, but Steve is a nice boy. It’s a terrible thing.”

An FBI poster issued after the escape said Benjamin Hoskins Paddock had been “diagnosed as psychopathic” and should be considered “armed and very dangerous.” He’d been serving a 20-year sentence for a string of bank robberies in Phoenix.

The elder Paddock remained on the lam for nearly a decade, living under an assumed name in Oregon. Investigators found him in 1978 after he attracted publicity for opening the state’s first licensed bingo parlor. He died in 1998.

Stephen Paddock bought his one-story, three-bedroom home in a newly built Mesquite subdivision for $369,000, in 2015, property records show. Past court filings and recorded deeds in California and Texas suggest he co-owned rental property.

He previously lived in another Mesquite — the Dallas suburb of Mesquite, Texas — from 2004 to 2012, according to Mesquite, Texas, police Lt. Brian Parrish. Paddock owned at least three separate rental properties, Parrish said, and there was no indication the police department had any contact with him over that time.

He has been divorced at least twice, including marriages that ended in 1980 and 1990. One of the ex-wives lives in Southern California, where a large gathering of reporters congregated in her neighborhood. Los Angeles police Sgt. Cort Bishop said she did not want to speak with journalists. He relayed that the two had not been in contact for a long time and did not have children.

In 2012, Paddock sued the Cosmopolitan Hotel & Resorts in Nevada, saying he slipped and fell on a wet floor there. The lawsuit was eventually dismissed by a judge and settled by arbitration.

Reached by telephone, Paddock’s lawyer at the time, Jared R. Richards, said he could not comment because of client confidentiality concerns.