Scotland Yard has launched an investigation into allegations that a Lib Dem peer sexually harassed activists.
The force said officers have looked into whether there are witnesses who would speak to police and are now investigating if there is corroborating evidence to back up claims against Lord Rennard.
The Met Police investigation into Lord Rennard adds to the two being run by the Liberal Democrats
The peer is accused of behaving inappropriately towards a number of women in the party, but has repeatedly denied any wrongdoing.
A Metropolitan Police spokesman said: "As is standard in cases of an historic nature, officers' initial inquiries are made to establish if allegations of crime are being made and if there are potential victims and witnesses who are prepared to speak to police.
"Officers then carry out inquiries to corroborate those allegations, and in this case that process is ongoing.
"We are not prepared to discuss who, how many or the nature of the allegations made by those who have come forward to police."
Officers from the Met's Special Investigations Command were approached by party officials in February, and at that stage the force said it was "working with them to ascertain whether or not criminal activity has taken place."
The Liberal Democrat Party is also running two internal inquiries.
A Lib Dem spokesman said: "The police are continuing their ongoing investigation into allegations made against Chris Rennard.
"The party continues to liaise with the Met, and has been since the allegations were first raised by Channel 4 in February.
"The party encourages anyone with information they feel may assist the police with their inquiries to contact them."