11:10 AM PT -- We just obtained the complaint, which lists 20 criminal counts, including one for possession of more than 600 images of children in porn, which includes 10 or more of a prepubescent minor. Most of the counts involve sexual exploitation of a child.

10:56 AM PT -- We've obtained Paddock's booking photo.

The brother of Vegas shooter Stephen Paddock has been arrested for child porn ... TMZ has learned.

Bruce Paddock was taken into custody moments ago in North Hollywood, CA at an assisted living home.

Law enforcement sources tell us ... cops were tipped that there was child porn on his computer and they got a search warrant. Our sources say the investigation began before his brother, Stephen, shot up the Vegas music festival earlier this month.

Our sources say before the shooting cops were trying to locate Bruce without success, but after his brother committed his heinous act a tip came in Bruce was living at an assisted living facility.

Cops say they found child porn images on his computer.

The arrest was made by a joint task force that included the FBI and LAPD.