As a child, Guy Edward Bartkus enjoyed playing with smoke bombs and model rockets, and once managed to burn down his family home with a box of matches.

On Saturday, authorities believe the 25-year-old blew himself up with a car bomb in Palm Springs, California outside a fertility clinic.

Following the blast, which killed Bartkus and injured four other people, investigators unearthed writing online and what appears to be an audio manifesto justifying the attack, in which he describes himself as a “pro-mortalist”.

He appeared to subscribe to an ideology that humans should cease to exist to prevent future suffering, and that having children is fundamentally immoral because they could not consent to being born.

Richard Bartkus, 75, the father of the suspect, has said that he believed the voice on the recording belonged to his son and suggested he had been “brainwashed” from spending time online.