Mark Dobson and Sarah Field, who served alongside Neil Taggart in the Garforth and Swillington Labour Party, say they feared he would evade justice on a technicality after details of the case were published in a national newspaper last year.
Earlier this week, the 65-year-old was jailed for 32 months after admitting downloading 36,000 indecent images of children over a six-year period and sharing images of children being abused using file sharing websites.
Taggart, who served as a Leeds city councillor between 1980 and 2014, was Lord Mayor of Leeds in 2003/04 and served as chairman of West Yorkshire Police Authority between 1998 and 2003.
Councillor Dobson and Councillor Field left Labour to form their own independent group in February and now say the party’s handling of the investigation into Taggart was part of the reason for their departure.
They said in a statement posted on Facebook that “senior party figures who did know were openly discussing the matter”, which led to the story being reported by The Sun.
Coun Dobson wrote: “The loose tongues of some meant that the case found its way into The Sun some months ago.
“Sarah and I were both seriously concerned that any decent defence team, should he have pleaded not guilty, would have claimed that, because of the leaks and the fact it had found its way into the media, he couldn’t get a fair trial.
“We were massively concerned the case would be dismissed on a technicality and he would evade justice.
“We were terrified he could walk away from justice because some in authority couldn’t help but gossip. To say we were both very angry is again an understatement.”
He added: “I’ve given all my evidence to the police who were ‘distraught’ by the leaks as were we.”
A spokesperson for Yorkshire & The Humber Labour Party said: “The Labour Party has made no comment that may jeopardise this case. The Labour Party is not however responsible for the actions of individuals who may or may not have been members of the Party. This is a matter for the police and courts if a contempt of court has taken place.”
Leeds Crown Court was told this week that Taggart’s personal reputation as a long-standing public servant has been “utterly destroyed” by his conviction.
Police armed with a search warrant raided his home in Marlowe Crescent, Garforth, on September 23 last year while he was on holiday abroad with his family.
Labour say Taggart was suspended in October, which was when officials became aware of the allegations he was facing.
In his statement, Coun Dobson said: “The party did not remove him on finding out the police action against him, this was several weeks later and not until after the most serious protestations that he had to go from Sarah and I.”
The Labour spokesman said: “The Labour Party does not take action on the basis of rumours and innuendo. As soon as the Labour Party became aware of the identity of this individual, it took measures to safeguard other members locally by applying an administrative suspension.
“Following a conviction in accordance with the Party’s rules Mr Taggart was automatically excluded from membership of the Party.”