UPDATE: Redmond will appear in front of Judge Keith Schwartz Thursday morning at 8:30 a.m.

Redmond O'Neal tested positive for drugs on Saturday, while in his current West Los Angeles rehab facility, and the dirty test is being reported to the court, RadarOnline.com is exclusively reporting.

O'Neal, 26, was arrested several weeks ago for heroin possession and later pled no contest to the felony charge. Rather than sending him back to jail, Judge Keith Schwartz sent him to rehab for a year.

Redmond's latest relapse could spell big trouble for him as he was already on felony probation for a previous heroin possession charge. Judge Schwartz minced no words for the son of late actress Farrah Fawcett and warned him this was his last chance, or he would be going to state prison.  As RadarOnline.com previously reported, Ryan O'Neal visited Redmond against his doctor's order the first day Redmond checked-in to the facility.  Ryan has only visited Redmond once in rehab.

The University of Texas has hired a private investigator to search for a missing $30 million Warhol portrait of Farrah Fawcett, and they're zeroing in on her former lover Ryan O'Neal.

In her last will and testament, as first published on RadarOnline.com, the late Charlie’s Angels star left her extensive and treasured art collection to her alma mater, including two matching Warhol portraits.

While one was given to the university, the other had been unaccounted for.

PHOTOS: Farrah Fawcett Through The Years