PORTLAND, Maine — The man charged with being the mastermind behind a scheme to distribute more than 10 pounds of cocaine and oxycodone pills in northern Maine pleaded guilty to drug charges Tuesday in U.S. District Court.

Michael Mayer, 55, of Jupiter, Fla., and Costa Rica pleaded guilty to conspiracy to possess with intent to distribute controlled substances.

Mayer, according to prosecutors, lived a lavish lifestyle fueled by cash. In pleading guilty, he also agreed to forfeit money and items purchased from the proceeds of his drug sales, including four pieces of property in Costa Rica, a pickup truck, a sport utility vehicle, a GMC Sierra and a boat used to pick up cocaine in the Bahamas, according to court documents. Mayer also agreed to forfeit $149,000 in cash.

Between January 2002 and June 2005, Mayer supplied large quantities of cocaine and diverted oxycodone, a powerful painkiller, to midlevel and street-level dealers in Maine, according to a press release from the prosecutor’s office.

Mayer sometimes had his co-conspirators transport the drugs from Florida to Maine, and at other times did it himself, according to the press release. He would meet with area distributors, mainly from the Lincoln-Lee area, to collect the proceeds from the drug sales.

After an alleged dispute between Mayer and his buyers in Maine over money, Assistant U.S. Attorney Joel Casey said last year, members of the drug ring obtained cocaine from June 2005 through November 2005 from Laurent “Larry” Provost, 60, of Woonsocket, R.I., who then was living in Mansfield, Mass. The relationship between the Maine buyers and Provost ended after less than six months in a disagreement over money and the quality of the drugs, according to court documents.

The group then turned to two people from the Dominican Republic who were operating out of Lawrence, Mass. Prosecutors have not named them. They were arrested in New Hampshire on unrelated drug charges in January 2006 and are serving federal prison terms, Casey has said. Where the ring obtained drugs after that has not been made public.

Mayer and Provost were indicted in November 2007 along with more than a dozen others. Mayer was arrested in Costa Rica sometime after that and extradited to Maine in October 2008.

Provost has pleaded guilty to drug conspiracy charges and Social Security fraud.

Both men face a minimum of 10 years in federal prison and a maximum of life and a fine of up to $4 million. In a plea agreement with the U.S. Attorney’s Office, Mayer waived his right to appeal his sentence to the 1st U.S. Circuit Court of Appeals in Boston if his sentence is not more than 17½ years.

Provost waived his right to appeal as long as his sentence is not longer than 37 months, according to his plea agreement.

Mayer and Provost are being held without bail pending sentencing. Mayer’s sentencing is scheduled for Sept. 30 at federal court in Portland. Provost’s sentencing date has not been set.

Kenneth Kaczmarski, 43, of Jupiter, Fla., was the last of the 18 defendants in the case to be arrested. He pleaded not guilty on June 10 to a drug conspiracy charge after being picked up in Florida. His trial date has not been set.

Five other defendants — Troy Littlefield, 42, of Oakfield, Nancy Squegilia, 51, of East Millinocket, Brent “Cowboy” Noyes, 57, of Lincoln, Richard “Rat” Russell, 48, of Lincoln and Jeffrey Whitehead, 54, of Enfield — are scheduled to go on trial on Aug. 11 in federal court in Bangor.

Lisa Delaurentiis, aka Lisa Fitzpatrick and aka Lisa Nylund, 41, of Jupiter, Fla., pleaded guilty to drug charges but later was allowed to withdraw her plea. Her case is pending.

The other defendants in the case all have pleaded guilty. They are:

Jeffrey Polk, 36, of Alaska.

Daniel “Danny” Littlefield, 49, of Lee.

Robert Donath, 28, of Lincoln.

Peter Glidden, 31, of Smithfield.

Mark “Goober” Russell, 41, of Lincoln.

Donald “Donny” Russell, 50, of Lincoln.

Preston Chubbuck, 43, of Springfield.

Raymond Davis, 48, of Lincoln and Jupiter, Fla.

Jeffrey Edwards, aka Bow Neck, 42, of Bradenton and Islamorada, Fla.

Donath and Edwards are scheduled to be sentenced in September in Portland. Sentencing dates for the others have not been set.

The Russells are brothers. The Littlefields are not related, according to prosecutors.

Mark Russell and Whitehead are serving sentences out of state.