Dr. Kachun C. Yeung pleaded guilty yesterday to two counts of prescribing the powerful pain medication Oxycodone "outside the course of professional medical practice and not for a legitimate medical purpose."

Undercover drug agents posing as medical patients twice met with Yeung in parking lots in Honolulu and paid him cash for prescriptions to Oxycodone, according to court papers filed yesterday.

Originally charged with 30 counts of illegally prescribing medications and 19 counts of welfare fraud, Yeung, 53, reached a plea agreement with federal prosecutors that could result in prison time and require deportation to Canada.

The painkiller — also known as OxyContin and "hillbilly heroin" — is widely abused.

According to papers filed by federal prosecutors in the case, the investigation of Yeung began after 11 patients who were being prescribed medications by him died of drug overdoses here between August 2000 and August 2002.

The government never alleged that Yeung was responsible for those deaths but filed the paperwork to refute allegations from Yeung's attorney that drug agents were unfairly targeting physicians specializing in "pain management."

The investigation was carried out by undercover agents of the U.S. Drug Enforcement Administration posing as patients of Yeung. According to the plea deal, Yeung met one of those agents, posing as a patient named "Jimmy Chang," in the parking lot of Panya Bakery on Auahi Street on the evening of June 14, 2002. Yeung wrote a prescription for 70 tablets of Oxycodone, and the agent paid him $400 in unreceipted cash.

A week later, Yeung and the same agent had another evening meeting in the parking garage of The Queen's Medical Center, and Yeung prescribed another 40 tablets of the medication, according to the plea agreement. Yeung and the agent "agreed on a $450 payment for the 'house call,' " the plea deal said.

Yeung faces a maximum penalty of 20 years in prison and a $1 million fine, but his ultimate punishment is expected to be considerably lower because he reached the plea agreement and agreed to deportation.

Sentencing will be held Aug. 30 before U.S. District Judge Helen Gillmor.

Last year, Yeung's son, University of Hawai'i student Christopher Yeung, posted photographs of DEA agents involved in the case on the Web site WhosaRat.com, dedicated to identifying law enforcement informants and undercover agents.

Christopher Yeung, who was a paralegal assisting in his father's case, obtained the images from government surveillance tapes turned over to criminal lawyers defending his father.

Assistant U.S. Attorney Jonathan M.F. Loo said Christopher Yeung's actions were not illegal because the Web postings occurred after the investigation was "essentially done."

But he continued: "Obviously, it's a concern. You don't expect materials turned over to the defense during discovery to be thrown out there for public consumption."

John P. Flannery, defense lawyer for the elder Yeung, said after yesterday's hearing that the physician "took responsibility" for his actions and is "actively seeking to make amends" for his conduct.

Reach Jim Dooley at jdooley@honoluluadvertiser.com.