March 4 (UPI) -- One of the United States' worst serial killers died Monday, the California Department of Corrections and Rehabilitation said.
Juan Vallejo Corona, 85, died of natural causes at around 8:15 a.m. at an outside hospital, the department said in a media release.
He was an inmate at the California State Prison-Corcoran.
Corona was serving 25 concurrent life sentences for having mutilated and murdered 25 farmworkers in 1971, which at the time made him the most prolific serial killer in American history.
The bodies were found buried in shallow graves along the Feather River in Sutter County, and as there were no witnesses, he was tried in 1973 on circumstantial evidence.
The victims were all men who had been seen with Corona and who had been hired through a county labor contracting business, the media release said.
Twenty-four of the men were hacked to death with a double-bladed ax, knife and a meat cleaver while the 25th victim was shot, CBS News reported.
While the Colusa County court found him guilty in January 1973, his conviction was overturned in 1978 by an appellate court, which said he wasn't given proper representation, earning him a new trial.
Corona was again found guilty on 25 counts of first-degree murder and sentenced to serve 25 concurrent years behind bars, with his sentence starting on Dec. 23, 1982.
In 1992, Corona was moved to the Protective Housing Unit at CSP-Corcoran, which houses inmates whose safety is jeopardized by the general prison population.
He experienced violence and health issues while in prison, including the loss of vision in one eye due to a repeated stabbing in 1972. He also suffered from at least three heart attacks while in prison.
Known as the "machete murderer," Corona was denied parole eight times with the most recent rejection in 2016. He was eligible for another hearing in 2021.