A gay con artist accused of murdering his partner said he had started looking at suicide websites and injecting vodka for a "thrill" before he died.
Gareth MacDonald, 30, was battered to death with a fire extinguisher in a Travelodge hotel room at the M4 Heston services in September 2007.
Mr MacDonald, a father-of-three, had left his wife and children to move in with Glenn Rycroft in Rhewl, North Wales, after meeting him on the internet.
Rycroft, a former British Airways steward, was a prolific conman who had previously cheated friends and colleagues out of more than £200,000.
The 33-year-old, originally from Salford, Greater Manchester, told an Old Bailey jury today that the pair would often use gay chat sites on the internet.
But he said he then discovered that his boyfriend, a diabetic, was also doing "searches relating to suicide with insulin blood poisoning".
Rycroft added: "I found out that he was injecting himself with stuff that wasn't insulin and that it was vodka on one instance and also cleaning fluid on another.
"I'd found chat messages asking how the thrill had gone with the vodka."
Rycroft said he made these discoveries about two months before Mr MacDonald died.
"He said it was to give him a thrill because the information that he had been given through the social networking sites about vodka was that it gives you a rush and makes you feel drunk quickly.
"It went to an extreme though because he started doing it quite a lot which, in my opinion, caused him to become ill."
The court has heard that Mr MacDonald was suffering poor health and spent several spells in hospital in the period before he died.
Rycroft said: "He was abandoning taking insulin for days on end when he was having a really low mood."
He denies murder.