Boston, who released a statement last week saying he had done nothing wrong, was arrested Aug. 23 when police said he was found slumped over the steering wheel of a red Range Rover with the SUV running and in drive.

A breath test taken at the scene was negative for alcohol. Boston was arrested pending the results of tests for other substances.

The results of the urine test were returned last week and submitted to the Pinellas-Pasco County state attorney's office.

Police said today that an initial positive reading for GHB, or gamma hydroxybutyric acid, was verified by a second independent lab.

GHB is a central nervous system depressant often called the "date-rape drug" because it leaves people groggy and powerless. Among other things, it is also said to have body-building effects.

"We are taking the allegations in today's report released by the Pinellas Park Police Department very seriously and we will continue to review all information as it becomes available," Bucs general manager Bruce Allen said in a statement. "We will reserve further comment until all the facts surrounding the investigation are complete."

The team has been supportive of the 29-year-old receiver, who was a rising star before injuries and suspensions derailed his career, which has also included stints with the Arizona Cardinals, San Diego Chargers and Miami Dolphins.

The eighth-year pro missed most of the past three seasons because of knee injuries. He also was suspended four games in 2004 for violating the NFL's steroid policy.

Boston, the eighth player selected in the 1999 draft, has 315 career receptions for 4,699 yards and 25 touchdowns. He signed with the Bucs in May and made the team after impressing coaches in training camp for the second straight summer.