Christopher Jefferies, the former public school teacher whose arrest over the murder of Joanna Yeates sparked a tabloid frenzy, has claimed lurid newspaper headlines may have encouraged the police to think they had caught the killer.

Speaking at a debate on Friday in his home city of Bristol, Jefferies said detectives seemed particularly interested in some of the "fantastical stories" about him during his questioning.

Jefferies said he was the victim of a "character assassination" by elements of the media. He said he was presented as a "dark, macabre, sinister villain … a lewd figure … a peeping Tom".

He added: "Because of the nature of the reporting, it merely served, I think, to encourage the police in their belief that they may have caught the actual murderer. Certainly, it was quite striking that during the interrogation of me the police were particularly interested in some of these fantastical stories that were being reported."

Jefferies, Yeates' landlord, was eventually released from police custody without charge and her neighbour, Vincent Tabak, was found guilty of her murder. Jefferies received apologies and damages from eight newspapers over allegations they made about him. The Sun and Daily Mirror were fined for contempt of court for their coverage.

Appearing at the Benn Debate 2012 on the future of the media, hosted by Bristol National Union of Journalists, Jefferies said the story of Yeates' murder just before Christmas 2010 and his subsequent arrest was a gift to the tabloids, a "ready-made Midsomer Murders script set in an apparently respectable, leafy suburb".

He spoke of how Yeates was depicted as "young, attractive, vulnerable, home-loving, at the start of what was going to be an extremely successful career. She was about to spend her first Christmas with her boyfriend. All this was suddenly destroyed and her body dumped callously by the side of the road."

The search for a "depraved monster" began. "I was the person that had been arrested," he said. "Certain parts of the press seemed determined to believe the person who was arrested was the genuine murderer and to portray me in as dark and lurid a light as possible."

He recalled how the Yeates' case was linked in the media to the unsolved murder of a second woman and how his "tenuous connection" to someone imprisoned for an offence against a boy had been flagged up.

Jefferies, who has appeared at the Leveson inquiry into media ethics, said he was shocked at how "casually inaccurate" some reporting was, such as a claim that floorboards were being pulled up in a flat with solid floors.

Asked why he had been arrested at the end of 2010 but not formally released from police bail until March 2011, Jefferies said the police had told him they wanted to be 100% certain they had probed every possible line of investigation. He said he was still involved in ongoing legal action against Avon and Somerset police.

Jefferies said he had stayed away from his flat in Clifton for three months after he was released from custody and only began reading some of what had been written about him when his lawyers asked him to do so. "Even today, I haven't been able to bring myself to read everything," he said.