PORTLAND — A man who authorities say operated a sprawling prostitution ring at his Oregon strip clubs pleaded guilty Wednesday to felony conspiracy charges and was expected to be out of prison by the end of the month.

Lawrence Owen, 75, entered guilty pleas in federal court to conspiring to defraud the Internal Revenue Service and conspiring to use an interstate facility — automated teller machines at the clubs — to promote prostitution in the Portland area.

After the pleas were entered, U.S. District Judge Michael Simon sentenced Owen to 2 ½ years in prison.

Owen has been behind bars since he was arrested at the U.S.-Mexico border more than two years ago. With credit for time served and good behavior, he could be free in two weeks.

Since the 1980s, Owen has operated more than a dozen adult-themed businesses, mostly strip clubs, in a city frequently cited as having the highest number of strip clubs per capita in the United States.

At Owen's clubs, customers could buy a 30-minute private show from dancers for $160, and it was understood that the stripper would engage in an act of prostitution, prosecutors said.

For each show, prosecutors said, the owner took a $60 cut.

All transactions were in cash and ATMs were on the premises. Throughout the five-year period cited in the indictment, more than $10 million passed through on-site ATMs.

Since 2006, Owen had been managing the businesses from Mexico, where authorities say he built and operated a brothel and has a 7-year-old daughter.

Defense attorney Noel Grefenson sought a lenient sentence, saying his client might otherwise die in prison without ever again seeing his daughter.

"Mr. Owen, your honor, is quite ill," the lawyer said. "He's had a hard time while incarcerated."

The judge did not admonish Owen before handing down the sentence. However, he asked Owen if he failed to file tax returns because he didn't feel like it or because he didn't want to alert authorities to his ill-gotten gains.

Owen mumbled a string of words, one of them was "disarray," before saying he didn't know.

Three co-conspirators, Owen's adult stepchildren and the manager of several of the strip clubs, previously pleaded guilty to conspiracy charges and will be sentenced in June.

The case began seven years ago, when IRS agents and police seized 85 boxes of records and $843,000 at the businesses and residences.

The seized cash has been forfeited to the United States. Proceeds from a $2.3 million sale of strip-club property in northeast Portland was placed in trust to pay taxes, penalties, and interest owed to the IRS.