Claims of election fraud are being investigated by police after fake election pamphlets were reportedly handed out in the name of a candidate.
Leaflets purporting to be from a Liberal Democrat candidate appeared to pledge support for a number of causes, including a controversial planning decision.
They were handed out the day before the Richmond Upon Thames Council by-election in south west London on May 4.
A Lib Dem spokesman said candidate Jane Dodds had not backed the manifesto points on the fake flyer.
The hotly contested Richmond North seat was won by Conservative candidate Stephen Speak, who beat Ms Dodds by 146 votes.
A Scotland Yard spokesman said officers were looking into the claims.
He said: "The Metropolitan Police Service is aware of an allegation of a breach of election legislation in Richmond.
"We are currently making an assessment to ascertain whether there is evidence to support the complaint."
The by-election took place at the same time as the London Assembly and London mayoral elections.