PORTLAND, Maine — Three defendants charged in the Lincoln-Lee cocaine distribution ring pleaded guilty this week to federal drug charges and to funneling 11 pounds of cocaine from Costa Rica and Florida into northern Penobscot County.

Jeff Polk, 36, of Lincoln and Anchorage, Ala., pleaded guilty Thursday in U.S. District Court in Portland to conspiracy with the intent to distribute cocaine.

Polk distributed cocaine to co-conspirators and collected proceeds from the sales, according to the U.S. Attorney’s Office. When he accumulated a significant drug debt, Polk agreed to work it off by making runs to and from Florida.

He admitted driving vehicles that contained hidden amounts of cash from Maine to the leader in Florida and making return trips with cocaine hidden in his car, according to prosecutors.

Raymond Davis, 48, of Lincoln and Jupiter, Fla., and Donald “Donny” Russell, 50, of Lincoln pleaded guilty Monday in federal court in Bangor to the same charge as Polk. Russell, who is legally blind and received disability, also pleaded guilty to Social Security fraud.

The three are being held without bail pending their sentences. Dates to sentence the men are not expected to be set until next year.

The men admitted to distributing cocaine that they obtained through Michael Mayer, 55, of Jupiter, Fla., and Costa Rica between Jan. 1, 2002, and June 1, 2005. Mayer has pleaded not guilty to drug charges.

In all, 18 people have been indicted in the drug distribution ring. All but one, whose name has not been released, have been arrested.

A fourth man, Peter Glidden, 31, of Smithfield, is scheduled on Jan. 6 to plead guilty in federal court in Portland to similar charges of conspiracy to distribute cocaine.

Each of the four men faces a mandatory minimum sentence of 10 years in federal prison and a maximum of life and a fine of up to $4 million on the drug charges. All four have signed plea agreements with prosecutors that would prevent them from appealing sentences longer than the 10-year mandatory minimum to the 1st U.S. Circuit Court of Appeals in Boston.

Russell also faces up to five years in prison and a fine of up to $250,000 on the fraud charge.

The four men also agreed to forfeit their profits from the drug operation to the government. Davis and Glidden agreed to forfeit $240,000 each, the amount prosecutors estimated they made from their cocaine sales. Polk agreed to forfeit $624,000, and Russell agreed to forfeit an amount to be determined before his sentencing, according to court documents.

Two other defendants, Laurent “Larry” Provost, 60, of Woonsocket, R.I., and Preston Chubbuck, 43, of Springfield also have pleaded guilty to drug charges.

A trial date in federal court in Bangor has been tentatively set for Feb. 3 for the remaining defendants.

Others who have pleaded not guilty in the case are:

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

• Lisa Delaurentis, aka Lisa Fitzpatrick and Lisa Nylund, 41, of Jupiter, Fla.

• Daniel “Danny” Littlefield, 49, of Lee.

• Troy Littlefield, 42, of Oakfield.

• Robert Donath, 28, of Lincoln.

• Nancy Squeglia, 51, of East Millinocket.

• Brent “Cowboy” Noyes, 57, of Lincoln.

• Richard “Rat” Russell, 48, of Lincoln.

• Mark “Goober” Russell, 41, of Lincoln.

• Jeffrey Whitehead, 54, of Enfield.

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

Mark Russell and Whitehead are serving sentences on unrelated charges out of state.