Police have concluded no criminal offences were committed in the Peterborough by-election following an investigation into a fifth and final allegation of electoral fraud.
Cambridgeshire Police had already found no evidence of wrongdoing after probing an allegation of ballot-burning, a report of bribery, and two claims related to postal votes.
The force said on Tuesday it had also now found no offences were committed in relation to a fifth allegation of a breach of voting privacy.
Labour’s Lisa Forbes won last month's election, beating the Brexit Party into second place by 683 votes.
Weeks later Nigel Farage's Brexit Party claimed vote-rigging may have played a role in the narrow victory and called for an inquiry.
The party’s chair Richard Tice said there had been numerous “rumours” of electoral fraud, while the Conservative deputy leader of Peterborough City Council also alleged there had been “harvesting” of postal votes.
Mr Tice also claimed to have evidence a former local Labour party secretary convicted of forging votes in Peterborough's 2004 council vote had acted as an agent for the party in last month's by-election.
Labour rubbished the allegation as "nonsense" and said claims of electoral fraud were a "desperate attempt" to excuse defeat.
The 6 June by-election was held to elect a replacement for Labour's Fiona Onasanya, who became the first MP be removed from office through a recall petition after being found guilty of lying to avoid a speeding ticket.