BOSTON - The ninth-season winner of reality TV show “Big Brother” has confessed to using his $500,000 prize to buy thousands of oxycodone pills and resell them, authorities said.

Adam Jasinski, 31, of Delray Beach, Fla., has been charged with attempting to sell 2,000 pills in Massachusetts to a government witness.

Federal prosecutors said Jasinski was arrested Saturday after he flew to Boston and showed the witness a sock containing two plastic bags filled with oxycodone, a powerful painkiller that is a popular street drug because of its euphoric effects.

As agents tried to arrest Jasinski at a strip mall in North Reading, he struggled and threw the sock under a car parked nearby, Todd Prough, a special agent with the Drug Enforcement Administration, said in an affidavit filed in court.

Jasinski won $500,000 on “Big Brother 9” in April 2008. The CBS reality show features contestants who live under constant surveillance and vote once a week to evict each other in hopes of becoming the last houseguest standing and winning the grand prize.

Prough said in the affidavit that Jasinski told him that he has been using his winnings to buy thousands of oxycodone pills and has been reselling them along the East Coast for the past several months.

Jasinski’s lawyer, Valerie Carter, did not immediately return a call Tuesday.

He faces a maximum of 20 years in prison and a $1 million fine on a charge of possession of oxycodone pills with intent to distribute.