The prime suspect in the Madeleine McCann case is facing new charges ahead of a trial.
Christian Brueckner is facing charges over alleged jibes made at prison guards.
The convicted German sex offender became linked to the Madeleine case two years ago.
It had emerged he had reportedly been driving around the Praia da Luz resort around the time the three-year-old went missing back in 2007.
Madeleine McCann (left) and prime suspect Christian Brueckner (right)PABrueckner, 47, is currently serving a prison sentence in Germany for the rape of a 72-year-old woman.
He is set to stand trial next month over five more alleged sex crimes. Now, it has been reported he is said to have described two prison officials at Oldenburg JVA in north west Germany as "torturers."
He had used the phrase in a complaint to prison authorities about the treatment he received at the jail.
Wardens complained to prosecutors after governors dismissed his complaint, saying his language was insulting.
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Kate and Gerry McCann, the parents of the missing 4-year-old British girl Madeleine McCannGETTYA third prison officer has since joined the complaint, saying Brueckner called him a "son of a b***h".
The Oldenburg public prosecutor’s office has filed charges of insulting public officials during the performance of their duties.
Brueckner is due to be tried next month over five alleged sex crimes, three involving minors. They include three rapes, one of an Irish girl, Hazel Behan, who was just 20 when she was said to have been attacked during a four-hour ordeal in Portugal.
Two other rapes are understood to have been filmed at the small farmhouse he rented just outside Praia da Luz, where British youngster Madeleine McCann went missing in May 2007.
He is also facing the sexual assault of a young German girl, 10, on a beach near Praia da Luz, a month before Madeleine went missing. Lawyers for Brueckner say prosecutors are wasting time and money on the lesser allegations of prison official abuse, calling it "farcical".
His lawyer Friedrich Fuelscher said: "This accusation is really farcical. First of all, the term 'torturer’ in the context of a criminal complaint by the accused should not be punishable under Section 193 of the Criminal Code. Anyone who criticises a state measure may also do so in an exaggerated manner.
He added: “However, even if admissible, public prosecutors regularly dismiss trivial cases if the punishment to be imposed is not significantly significant compared to the punishment that can be expected for another crime.
"This regulation cannot be more relevant than in the Brueckner case." He also called the charges "a massive waste of tax money.”