The U.S. Justice Department is investigating some of Baton Rouge-based home nursing giant Amedisys Inc.’s hospice operations in Massachusetts.

The company reported Thursday that the U.S. Attorney’s Office in Massachusetts had subpoenaed records for 53 hospice patients. Amedisys received the subpoena on May 21.

The U.S. Attorney’s Office also requested documents related to the company’s hospice clinical and business operations and related compliance activities, Amedisys said. The subpoena covers the period from Jan. 1, 2011, through the present.

“The company is fully cooperating with the U.S. Department of Justice with respect to this investigation,” Amedisys said in a report filed with the U.S. Securities and Exchange Commission. “No assurance can be given as to the timing or outcome of this investigation.”

It’s been close to 18 months since Amedisys announced a $150 million settlement with the Justice Department over Medicare bills for home nursing. Amedisys said it settled to avoid a protracted and expensive legal battle. The company admitted no wrongdoing.

The Justice Department alleged in that probe that Amedisys inflated its Medicare payments, charging Medicare for medically unnecessary treatments and for treating patients who were not homebound.

That investigation covered a period ending in 2010. It was one of three federal probes — the others were by the SEC and the U.S. Senate Finance Committee — over Amedisys’ billing practices.

Those investigations sent Amedisys and its shares on a long downward slide that culminated in the legal settlement and founder and CEO William Borne’s departure.

Amedisys provides home health and hospice care to about 360,000 patients each year.

Amedisys stock dipped 13 cents in after-hours trading to $31.70 Thursday, after gaining 16 cents during the trading day.

Follow Ted Griggs on Twitter, @tedgriggsbr.