Unanswered questions about Vegas?

A brother of Las Vegas shooter Stephen Paddock has been arrested for child pornography.

Bruce Paddock, about 58 years old, was arrested Wednesday at an assisted living home in North Hollywood, California, law enforcement sources tell TMZ.

Bruce had been under investigation for child porn since before the October 1 shooting, but officials didn't know where he was living.

After the shooting, they got a tip about Bruce's whereabouts and tracked him down to the assisted living center where they found child porn images on his computer.

A joint task force that included the FBI and LAPD made the arrest.

Bruce lives a 'nomadic life' and has a long criminal history including convictions for petty theft and vandalism, TMZ previously reported.

Bruce also threatened to murder a property owner in 2014, while he was squatting at a home in the San Fernando Valley.

The home owner, Hector Cruz, said after he complained to Bruce about him tampering with machinery and equipment and Bruce snapped.

He said Bruce got into a fighting stance with clenched fists and told him 'If you keep f****** with me I am going to kill you and drop you in the desert.'

Cruz described Bruce as a drug user, who sold meth and weed.

A judge granted Cruz's request for a temporary restraining order in that case.

Bruce and Stephen are also the sons of a bank robber who was on the FBI's Most Wanted List for nearly a decade, Benjamin Hoskins Paddock.

Benjamin was sentenced to 20 years in prison for a series of bank robberies in the late 50s and early 60s. But in 1968, he broke out of jail and went on the run.

He was put on the FBI's Ten Most Wanted Fugitives List form 1969 until 1977 - when he was caught at a bingo parlor he started in Oregon. He died in 1998 at a correctional facility in Texas at the age of 71.

During his lifetime, he was diagnosed as being psychopathic.

Stephen was the oldest of his four sons with Dolores Irene Hudson. The 64-year-old killed 58 people and injured more than 400 after opening fire from his sniper's nest in the Mandalay Bay hotel and casino on October 1. Stephen committed suicide as police stormed his room.

Stephen and Bruce have two other brothers. Youngest Eric, 57, lives in Florida near their 89-year-old grandmother and Patrick, 60, is an engineer in Tucson.

Police continue to search for a motive in the Las Vegas shooting.

Stephen's family have said that he didn't show any sign of mental illness and seemed to have his life together - after making millions from investing.

'My brother was the most boring one in the family,' Patrick Paddock told the New York Times. 'He was the least violent one in the family, over a 30-year history, so it’s like, who?'

But investigators have since discovered that Stephen started to show signs of angst in his final years, when he began to build up a massive stockpile of weapons.

Several people noted that he started to smell of alcohol often.

He was also reportedly prescribed the anti-anxiety drug Valium, which he was taking in its highest dose by June 2017.

The side effects of the drug - which include suicidal thoughts and unusual risk-taking behavior - can be magnified when mixed with alcohol.