"No evidence" of electoral fraud has been found in the Thanet South seat contested in the general election by Nigel Farage, police have said.
The UKIP leader failed to win the seat, losing out to Conservative candidate Craig Mackinlay.
Kent Police said initial investigations were prompted by contact from outside the county expressing concerns over social media speculation.
Thanet District Council said it was not under investigation for fraud.
In a statement it said police had an obligation to follow up the complaint.
"The council's returning officer is satisfied that the correct processes were followed and a member of the Electoral Commission was present at the election in Thanet," it said.
'Postal vote problems'
The election result was not declared at the count at Margate's Winter Gardens until about 10.35 GMT on Friday, hours later than expected.
BBC reporters were told by officials at the time the delays were caused by the sheer volume of ballot papers and problems verifying the postal vote.
Turnout was 69%, up from 65% in 2010.
Claims of suspicious behaviour appeared on social media following the delays.
The Twitter hashtag #thanetrigged gained momentum when UKIP claimed victory in the local council election, with the party taking control of the authority.
Some users said that UKIP's local council triumph so soon after Mr Farage's defeat pointed to suspicious behaviour in the parliamentary contest.
'No lost or stolen papers'
Thanet council said, in response to the speculation: "Thanet's parliamentary boundary is larger than the district boundary - extending into the Canterbury and Dover area - so comparing the parliamentary and district election results is misleading.
"There were no lost or stolen ballot papers."
Labour's South Thanet candidate Will Scobie, who received 11,740 votes, said he thought the count took a long time because they were "trying to do two constituencies at once".
Mr Mackinlay said he was "absolutely and completely" sure he was elected fairly and he added: "Let's see how this develops but I can't see there's anything in this."
Mr Farage secured 16,026 votes, with Mr Mackinlay achieving 18,838.
The Thanet South seat was also contested by Ian Driver of the Green Party, who got 1,076 votes, and Liberal Democrat Russell Timpson who secured 932 votes.
Both Mr Driver and Mr Timpson lost their deposits after failing to secure 5% of the vote.
Comedian Al Murray, who stood for election in the guise of The Pub Landlord for the Free United Kingdom Party, came in sixth place with 318 votes.
Mr Farage announced his resignation after failing to become an MP but this was rejected by his party and he continues to be UKIP leader.