Autopsies will be done on four inmates who died during the past several days after being hospitalized, the Mississippi Department of Corrections said in news releases.

The department said no foul play is suspected in any of the four deaths. At least 67 inmates have died in Mississippi prisons since late December. The U.S. Justice Department announced in February that it is investigating Mississippi’s prison system. Several inmates died during outbursts of violence in late December and early January.

Carl Magee, 63, was pronounced dead Friday at Greene County Hospital in Leakesville. He was taken there from South Mississippi Correctional Institution, where he was serving a 10-year sentence for possession of a controlled substance with intent to distribute. He was sentenced June 10, 2013, in Hancock County.

Malachi Lewis, 77, died Thursday at the hospital of the Mississippi State Penitentiary at Parchman, where he had been since late July. He was serving life for murder in Attala County. He was sentenced March 17, 1983.

David Harris, 81, died Thursday in the Parchman prison hospital, where had been for several months. Harris was serving 45 years for fondling and sexual battery. He was sentenced April 7, 2009, in DeSoto County.

Eddie Johnson Jr., 51, died Wednesday at Merit Health Central in Jackson, where he had been taken from Central Mississippi Correctional Facility. Johnson was convicted Feb. 15, 2010, of statutory rape in Scott County and sentenced to 15 years.

The Department of Corrections on Wednesday also released the name of an inmate whose death was previously announced. His identity originally was withheld until his family was notified.

Woodrow Winchester, 64, was pronounced dead Aug. 15 at Merit Health Central, where he had been taken from Parchman. Winchester pleaded guilty Jan. 17, 2007, in Itawamba County to four counts of sexual battery. He received 20 years on each count to run concurrently. The department said no foul play is suspected and an autopsy will be done.