Fallout from the "Plebgate" row intensified as Scotland Yard passed evidence to prosecutors and ex-cabinet minister Andrew Mitchell took legal action against the newspaper which broke the story of his verbal altercation with police officers.
The Crown Prosecution Service last night confirmed it had received "initial papers" from Scotland Yard in relation to the investigation, which was sparked by claims the then chief whip called officers "plebs" and swore at them repeatedly after being told he could not ride his bicycle through the gates of Downing Street.
Mitchell admitted there was an ill-tempered exchange and quit the cabinet but insists he did not use the words attributed to him and was the victim of a deliberate campaign to "toxify" the Tories and ruin his career.
He confirmed last night that his lawyers had issued a libel writ against The Sun, which first ran the story, as he continued a fightback.
A friend of Mr Mitchell said the MP had been subjected to a "campaign of vilification".
A spokesman for the newspaper said it stood by its story "and will defend this claim vigorously".
So far, three officers have been arrested as part of the investigation sparked by the row about the incident on September 19.
Those arrested include a 52-year-old from the Diplomatic Protection Group who was held on December 15 on suspicion of misconduct in public office and bailed until April.
Two 46-year-olds from the same command were held on January 31 and February 1 for allegedly passing information to the media and were bailed until May.
All three remain suspended. A 23-year-old man who does not work for the police was also arrested and bailed until May.
A CPS spokesman said: "We have received initial papers but we have not received a full file of evidence and we now await the conclusion of the police investigation before considering charges."
An email from a civilian witness backing up the police account of events has also since been called into question.
Some 30 detectives have taken statements from all 800 officers in the DPG, which is tasked with protecting government officials.
Scotland Yard is currently trying to find out how the Sun and Daily Telegraph obtained information about the "Plebgate" row and if it came from police.
It is also looking at a police officer's claim to have witnessed the altercation between Mr Mitchell and officers in Downing Street, and allegations by Mr Mitchell that police had lied in a log dated September 19 2012.
Pressure on Mr Mitchell intensified when The Daily Telegraph published the log.
Mitchell's lawyer Graham Atkins indicated that further legal action could follow.
"I can confirm that I recently issued proceedings for libel against the owners of The Sun on behalf of Andrew Mitchell MP," he said.
"There are a number of other potential actions being considered but I do not intend commenting any further at this stage."