Steve Bouquet, a former Royal Navy gunner, known as the "Brighton cat killer", has died.
The veteran and security guard was imprisoned last year over the deaths of nine cats and injuries to another seven.
Steve Bouquet (centre) is escorted away from Brighton Magistrates Court after appearing on 16 counts of criminal damage over attacks in Brighton on cats between October 2018 and June 2019.
Gareth Fuller
Mr Bouquet attacked the cats between October 2018 and May 2019.
He was caught on CCTV by the owner of one of the dead cats.
Mr Bouquet's death comes after the court heard during his sentencing that he was suffering with thyroid cancer that had spread to his liver and lungs.
However a formal cause of death is yet to be known.
"Steve Bouquet died at Maritime Medway Hospital on January 6 2022", a Prison Service spokesperson said.
"The Prisons and Probation Ombudsman has been informed."
Mr Bouquet was jailed for more than five years in July 2021. He was found guilty of 16 offences of criminal damage relating to the cats. He as also found guilty of possessing a knife.
Mr Bouquet was in the Royal Navy for 22 years and served in Northern Ireland and Iraq.
Judge Jeremy Gold QC told the court Mr Bouquet's behaviour was “cruel, it was sustained and it struck at the very heart of family life”.
He went on: “It is important that everyone understands that cats are domestic pets but they are more than that. They are effectively family members.
“They are much loved by the adults and children who live with and care for them.
“Cats and all domestic animals are a source of joy and support to their owners, especially during lockdown.”