Stahl031510_01_X17pic230crop.jpgActor Nick Stahl has checked himself out of rehab, against doctors' advice, and now the Terminator star has been missing for four days.

Stahl was last reportedly seen in Downtown LA over the weekend after staying at a friend's house, but after leaving, he never came back.

Before his most recent stint in rehab, Stahl went missing back in May for a week.

He apologized at the time to his wife and friends for "worrying everyone."

The actor has reportedly had a long history with drug abuse.