Mid Ulster voters going to polls
Voters in Mid Ulster are going to the polls in a Westminster by-election contest that has become heavily associated with a historic Troubles murder.
The race for the seat vacated by Martin McGuinness pits a unionist-unity candidate whose father was shot dead by the IRA against a Sinn Fein veteran who was once accused in the House of Commons of involvement in the killing.
Sinn Fein Assembly Member Francie Molloy has always vehemently denied the allegation levelled six years ago under parliamentary privilege by Upper Bann Democratic Unionist MP David Simpson that he was a suspect in the 1979 murder of former policeman Frederick Lutton.
The ex-Royal Ulster Constabulary reservist's son Nigel is standing in the election as an independent with the backing of Stormont's main unionist parties, all of whom have stood aside in a bid to maximise Mr Lutton's vote.
But the Portadown undertaker still faces a huge challenge to overturn Sinn Fein's 15,000-plus majority established by Mr McGuinness in 2010.
Stormont's deputy First Minister has resigned from the Westminster role he first secured in 1997, insisting he wants to focus on business at the Northern Ireland Assembly.
The two other candidates in the field are senior Social Democratic and Labour Party member and local MLA Patsy McGlone and former headmaster Eric Bullick, who is representing the cross-community Alliance Party.
The emergence of Mr Lutton as a unionist unity candidate has had major ramifications for the Ulster Unionist Party (UUP).
In the wake of the UUP's decision to back Mr Lutton, two of its high-profile Assembly Members - Basil McCrea and John McCallister - resigned in protest and have subsequently signalled their intent to form a new party.
The count will take place at Cookstown Leisure Centre and a result is expected in the early hours of Friday.