An opposition MP at the centre of a sex and drugs scandal was placed under investigation on Thursday.
Prosecutors said Cosimo Mele, a former member of the Catholic, centrist UDC party, was being investigated for drug pushing.
Mele was caught out after a prostitute with whom he spent the night at a luxury Rome hotel overdosed on cocaine and had to be taken to hospital.
The prostitute has told investigators that the 50-year-old MP supplied her and a girlfriend who joined them at the hotel with the drugs.
She also told them Mele failed to help her when she fell ill, an accusation which could complicate the MP's position.
Mele, who is married with three children, denies taking drugs and says he was the one who insisted the girl seek medical help.
The southern lawmaker resigned from the UDC party in disgrace after his Friday night antics became public.
The incident was a major embarrassment for the small party, which espouses family values and is currently pressing for MPs to take drug tests.
Mele, who has campaigned in the past on the need to "defend our Christian values and identity", is one of the advocates of the drug-testing policy.
But the UDC also drew ridicule and indignation when its leader Lorenzo Cesa suggested Italy's highly-paid politicians be given a rise to allow their wives to join them in Rome.
"The life of an MP is hard and solitude is a very serious thing," Cesa said.
The incident was not the first run-in with the law for Mele, who is also a construction businessman.
He was arrested in 1999 while serving as deputy mayor of his hometown of Carovigno in Puglia for allegedly taking kickbacks on public works contracts. A trial is still under way.
MP AND PROSTITUTE TELL DIFFERENT STORIES.
Mele said in interviews published earlier this week that "I didn't take drugs and it wasn't a threesome".
He said he was introduced to the prostitute by friends while dining at a restaurant.
"We hit it off... I didn't even know she was a prostitute," Mele said.
"I only realised later. I didn't exactly pay her. Instead I gave her a present - some money," he said.
The lawmaker went with the woman to the Hotel Flora on Via Veneto, which features in Fellini's 1960 classic La Dolce Vita.
He says that she called a friend to join them in their suite and that he watched television while they chatted.
He claims to have been sleeping when the two starting sniffing cocaine.
"When we were alone again, she (the prostitute) began to feel bad. She seemed to be hallucinating. She didn't want me to but I did what I thought was right and immediately called an ambulance. Before that, I called reception to see if there was a doctor around," the MP told Rome daily Il Messaggero.
In another interview with the Corriere della Sera, Mele said that he was "proud" of himself.
"I realised when I called the ambulance that my name could come out. A lot of other men would have just taken off," said the MP.
He admitted he was worried about how his second wife, who is heavily pregnant, would take it all.
The prostitute, meanwhile, told reporters that Mele was lying.
She told La Repubblica daily that she and her friend spent the night with Mele and that "nobody slept".
When asked if Mele had called her an ambulance when she fell ill, she replied: "You must be joking. He tried to grab my cellphone out of my hands. I called my companion and my brother for help".
The UDC said Mele's behaviour was "contrary to party values".
The party went ahead with a "symbolic" anti-drugs demonstration on Wednesday which involved voluntary drug testing for MPs outside parliament.
A cult TV show caused uproar last year by exposing allegedly widespread drug use in parliament.
The show Le Iene secretly tested 50 MPs for drugs, revealing that one in three had apparently taken them in the preceding 36 hours.
Twelve tested positive for cannabis and four for cocaine, Le Iene said.
The prank never aired because of protests by MPs who claimed their privacy had been violated.
