Police said Reardon stabbed his partner, a man in his 20s who police are not naming, in the back and throat as they walked through the woodland, near Slough, on Friday, 23 May.
Detectives said he had asked to use his partner’s mobile phone which he then used in an attempt to send a message to the victim’s mother “suggesting the victim had suicidal thoughts”.
However, the message failed to send, and the victim saw it just moments before Reardon launched his attack with a steak knife.
He continued to stab him, despite pleas for him to stop.
The victim was stabbed, struck with a candle and strangled, but managed to disarm Reardon twice and escape, police said.
The attack ended when the victim ran to a road and found a dog walker, who called emergency services.
At this point Reardon fled.
The victim had multiple and extensive serious injuries in the attack, but survived thanks to the expertise of medical professionals, police said.