Johnny Brewer, 41, was discovered at about 2:15 a.m. with a sheet around his neck at Kirkland Correctional Institution, a maximum-security prison, the state Corrections Department said.
He was immediately cut down but attempts to resuscitate him were unsuccessful, officials said.
Mr. Brewer, a convicted murderer, had been serving a life sentence when he and Jimmy Causey, a convicted kidnapper, escaped from a maximum security prison in November 2005.
Prison officials said the inmates used toilet-paper heads made by other prisoners to delude officers.
They also blamed the escape on staffing cuts and improperly compacted trash.
Corrections Department director Jon Ozmint said the escapees had observed trash compacting procedures and knew that if the trash bin wasn't full, they would not be killed.
Authorities captured Mr. Brewer and Mr. Causey two days after they escaped when they were recognized at a hotel by a pizza delivery woman.
The two were apprehended in Ridgeland, about 100 miles south of the prison where they had escaped.
Mr. Brewer was convicted of killing his sister-in-law, 23-year-old Kelly Burbage, in 1994.
The Corrections Department said it was investigating Mr. Brewer's death.