Prosecutors probed over £150,000 video meant to prove Knox's guilt

Two prosecutors who called for Amanda Knox to spend the rest of her life in jail after claiming she killed Meredith Kercher are now themselves under investigation.

Giuliano Mignini and Manuela Comodi are accused of wasting public funds on commissioning a controversial video, presented to jurors, which showed images of Ms Knox and her then boyfriend Raffaele Sollecito murdering the British exchange student.

Ms Knox, 24, was dramatically cleared of the killing last October when the appeals court in Perugia accepted that pivotal DNA evidence used to convict her and Mr Sollecito, 27, had been fatally flawed. A third person, an unemployed drifter Rudy Guede, is serving 16 years for the murder in November 2007.

Now, in a further embarrassment to Ms Comodi and Mr Mignini, both of whom staked their reputation on the case, the Umbria audit court prosecutor Agostino Chiappiniello has said he suspects the two of inappropriately spending €182,000 (£148,000) on a crude and cartoonish 20-minute video, which purports to show events leading up to and including the brutal slaying. It was shown during the original 2009 trial, which saw Ms Knox jailed for 26 years and Mr Sollecito for 25 years.

Both were freed last October. But they must wait until later this year to see if the Supreme Court of Cassation, Italy's highest criminal legal body, absolves them definitively of the murder charges. This is because in February this year the prosecution appealed to the court to reinstate the murder convictions.

The gung-ho Mr Mignini, who led the prosecution of Ms Knox in the first trial, is no stranger to controversy. Since their release, the friends and families of both Ms Knox and Mr Sollecito have criticised the investigating magistrate, who after leading the prosecution in the first trial, reappeared in the second, despite being accused of abuse of office in the interim in a separate case. In both trials, his interventions were notable for the outlandish motivations and personality traits he attributed to the defendants. He promoted the idea that the murder was the result of a sex-game that got out of control, despite having little or no evidence to support the theory. "That gentleman should understand once and for all that he was wrong," Mr Sollecito's father, Francesco, said after his son's release.

Last October, the chief appeals judge, Claudio Pratillo Hellmann, said that both Ms Knox and Mr Sollecito were "completely innocent" of murder and assault ahead of the final appeal verdict by the Supreme Court of Cassation.

Judge Hellmann also criticised the conduct of the investigators after Ms Knox's arrest. "Her rights were ignored and she was not even appointed a lawyer, a right which she had, seeing as she was being accused of a serious crime."

Judges at the Cassation court may only overturn the first-appeal verdict on technical grounds. Thus, no new evidence may be introduced and the prosecution's room for manoeuvre is limited. The pair could not be retried for the same crimes. Ms Knox is back in her home town of Seattle in the US. Mr Sollecito has returned to university.