Born in Burton upon Trent, Staffordshire, England, Hardy had an apparently uneventful childhood and excelled in school and college. He earned an engineer's degree from Imperial College London and subsequently became a manager of a large company. Hardy married and fathered three sons and one daughter; his wife divorced him in 1986, accusing him of domestic violence. In 1982, Hardy had been arrested in Tasmania for trying to drown his wife, but the charges were later dropped.
After the divorce, Hardy spent time in mental hospitals, diagnosed with bipolar disorder. He lived in various hostels in London, picking up convictions for theft and being drunk and disorderly. He was arrested in 1998 when a prostitute accused him of raping her, but the charges were dropped due to lack of evidence. He became an alcoholic and diabetic.
In January 2002, police were called to the block of flats where Hardy lived after a neighbour complained that someone had vandalised her front door and that she strongly suspected Hardy. When the police investigated Hardy's flat, they found a locked door and, despite his claims to the contrary, found that Hardy had a key. In the room the police found the naked dead body of a woman lying on a bed with cuts and bruises to her head. She was identified as Sally White, 38, a prostitute who had been living in London.
Forensic pathologist Dr. Freddy Patel subsequently concluded that White had died of a heart attack, in spite of the circumstances. Patel later came under scrutiny for this and other findings in his career, including the 2009 death of Ian Tomlinson, resulting in a suspension from the government's register of pathologists pending an inquiry. In 2012, his name was erased from the medical register by the General Medical Council, meaning that he can no longer practise medicine in the United Kingdom.
Hardy pleaded guilty to a charge of criminal damage and claimed he had no knowledge of how White came to be in his flat due to his drinking problem. Whilst in custody Hardy was transferred to a psychiatric hospital, under section 37 of the Mental Health Act 1983, remaining there until November 2002.
On 30 December 2002, a homeless man scavenging for food in bins found some of the dismembered remains of two women, stuffed into bin-liners. The victims were identified as Bridgette MacClennan, 34, and Elizabeth Valad, 29. The investigation led to Hardy, who was arrested a week later. He had gone on the run, but was spotted by an off-duty policeman when he went to Great Ormond Street Hospital to collect his prescription for insulin. On-duty police arrived on the scene and during a search of the grounds of the hospital, Hardy was found hiding behind bins. A fight took place as he resisted arrest, during the course of which a police officer was knocked unconscious and another officer was stabbed through the hand and had his eye socket dislocated. Despite suffering these injuries, the wounded police officer held Hardy until backup arrived and he was arrested at the scene. A subsequent search of his flat found evidence, including old blood stains, indicating the two women had been killed and dismembered there. Both had died over the Christmas holidays.
Under arrest, Hardy simply said "no comment" to every question put to him by police. He was eventually charged with the murders of both MacClennan and Valad, and of White, the woman whose death had originally been put down to natural causes. At his trial in November 2003 Hardy, despite his initial lack of cooperation with the police, abruptly changed his plea to guilty to all three counts of murder and was sentenced to life imprisonment. Because of Hardy's history of psychiatric problems and violent behaviour, an independent enquiry was announced into his care.
Police have been reported to believe that Hardy is possibly connected to the unsolved cases of two prostitutes found dismembered and dumped in the River Thames, and up to five or six other murders that bore marked similarities to the ones for which he was convicted, but where not enough evidence is available directly implicating him.
Hardy has been diagnosed with a personality disorder. In May 2010, a High Court judge decided that Hardy should never be released from prison, placing him on the list of whole life tariff prisoners. Mr Justice Keith, sitting in London, said: "This is one of those exceptionally rare cases in which life should mean life."
Hardy was the subject of an episode of Evil Up Close on the Crime and Investigation Network, focusing on the 2010 decision to keep Hardy in prison for the rest of his life. The film was directed by Robert Murray and written and produced by Will Hanrahan. After Hardy was imprisoned British rap artist Plan B released a song about Hardy, dubbing him the 'Camden Ripper'. Hardy is also mentioned, and his flat pointed out, in the music video "Guided tour of Camden" by Charlie Sloth. Hardy was the subject of a Channel 4 documentary, The Hunt for the Camden Ripper, broadcast in 2004. It was narrated by Juliet Stevenson and directed by Olly Lambert.