Fayez Ayoub, whose name was included on a list of 36 wanted men earlier this week, flew home from Lebanon and handed himself over to Saudi authorities on Friday, the Interior Ministry said.
The ministry said in a statement carried by the official Saudi Press Agency that Ayoub had asked for "clarification" of his position.
It said his family would be allowed to meet him while his case was being investigated.
Most among the 36 listed suspects are believed to be outside the kingdom.
The ministry offered a bounty of up to seven million Saudi riyals ($1.87 million) for anyone who helped capture one of the suspects or foil any attacks.
Officials say at least 90 civilians and more than 40 members of the security forces have been killed by fighters and attacks have caused at least one billion riyals' ($270 million) worth of damage.
But police say they have killed more than 100 fighters in the same period and there have been no attacks this year comparable to the multiple bombings of residential compounds in 2003 or the killings of Westerners a year ago.