WESTBROOK – Federal agents have confiscated several boxes full of documents from a Westbrook methadone clinic.

Using a federal search warrant, agents with the Drug Enforcement Agency and the Department of Health and Human Services spent several hours Tuesday afternoon searching CAP Quality Care. Among the boxes that were removed were ones labeled as patient files.

Robert Hatch, an attorney who represents the clinic, said his client is cooperating with authorities. He said the clinic remains open.

“We are continuing to comply with the requests by authorities for documents at our clinic,” Hatch said. “We had no advance knowledge of their arrival yesterday, but provided them with the information they requested.”

Methadone, a synthetic narcotic, is widely used to help addicts control their dependence on drugs such as heroin, morphine or OxyContin, and lead productive lives.

But law enforcement officials have said that in recent years it has been a leading cause of fatal drug overdoses in Portland.

The deaths have raised questions about the screening process used to determine which patients are eligible to take doses of methadone home, and the size of the doses patients are given.