BANGOR, Maine — A Rockland woman who has admitted supplying a dose of methadone to her brother the day he died four years ago pleaded guilty to federal charges Tuesday in U.S. District Court in Bangor.

Rochelle Kenney, 47, pleaded guilty to distribution of methadone between December 2004 and December 2006 that resulted in a death and to health care fraud during the same time period that resulted in a death.

Under her plea agreement with federal prosecutors, a third count, distribution of diazepam, is expected to be dismissed at her sentencing.

By pleading guilty to the charges, Kenney admitted that she sold and-or gave away methadone that was paid for by Medicaid.

She will be held without bail pending sentencing.

A sentencing date has not been set but is not expected until late September or early October.

Kenney told U.S. District Judge John Woodcock that she was “nervous, confused and scared” during the nearly 90-minute hearing that reviewed what the judge called a “pretty complicated plea agreement.”

“I am guilty of giving my brother the methadone,” she said in entering her guilty plea.

She wept throughout the hearing and stopped several times to compose herself before continuing to answer the series of questions Woodcock is required to ask before accepting a guilty plea.

Her family members talked among themselves during the hearing. At one point, a U.S. marshal advised them to be quiet. They complied with that request.

Kenney’s brother John Kenney, 43, died April 26, 2005, six months after he and three crew mates survived the sinking of the 44-foot dragger Canadian Mist 30 miles southeast of Nantucket.

The day John Kenney died, his sister shared with him methadone she had picked up earlier in the

day from a Waterville clinic. Later that day, he flew with others in a private plane from Rockland to Matinicus Island to go on a fishing trip.

Shortly after they arrived on the island, he was found slumped over on a doorstep at the home of the person the group had come to visit, according to court documents. The autopsy showed that he died of “acute methadone and diazepam toxicity,” the state medical examiner determined in late 2005 after toxicology tests were completed.

The autopsy also showed that John Kenney suffered from “hypertrophic cardiovascular disease,” or an enlarged heart, which may have been a factor in his death, according to David Bate, the Bangor attorney for Rochelle Kenney.

It will be up to Woodcock to determine whether the methadone the defendant gave her brother was the sole cause of his death. If the judge finds it is more probable than not that the methadone caused John Kenney’s death, Rochelle Kenney would face a mandatory minimum sentence of 20 years in prison and a maximum sentence of life.

If Woodcock determines that the methadone did not cause the fisherman’s death, Kenney will face a maximum of 20 years in prison.

Bate said after the hearing that to send his client to prison for a minimum of 20 years, Woodcock must find that John Kenney wouldn’t have died except for the methadone dose his sister gave him. The fisherman’s methadone level was below the midrange of a therapeutic level, the defense attorney said.

“He had an enlarged heart,” Bate said. “He changed his heart medication the morning of his death. Also, he had been told not to go fishing offshore, where he would be far from emergency medical care, due to his heart condition.”

The attorney said that he plans to call the medical examiner for the state of Maryland as an expert witness at the sentencing hearing.

Assistant U.S. Attorney Joel Casey declined to comment on the case. It is the policy of the U.S. Justice Department not to comment on cases until they have been resolved.