Baciro Dabo had been standing as an independent candidate
Guinea-Bissau is to press ahead with presidential elections on 28 June, despite the killings of a candidate and ex-defence minister last week.
Authorities said the pair, shot dead by soldiers, had been plotting a coup.
Interim leader Raimundo Pereira said he decided to press ahead after consulting the government and political parties.
The last president, Joao Bernardo Vieira, was assassinated in March. Guinea-Bissau has been plagued by coups since independence in 1974.
However, independent presidential candidate Paulo Mendoca has filed a complaint to the Supreme Court, arguing it would be illegal to go ahead with the polls as the constitution calls for a delay if any of the candidates dies.
One of 13 presidential contenders, Baciro Dabo was a member of the ruling party but was going to contest the election as an independent.
The authorities said he had resisted arrest, but his friends insisted he had been asleep with his wife when he was shot. He was a close ally of the late president.
Former Defence Minister Helder Proenca, and two of his guards, were also shot last week in the West African country.
Mr Proenca - who was killed separately from Mr Dabo - was accused of being the mastermind of the alleged coup.
President Vieira was hacked to death with machetes on 2 March by soldiers who blamed him for a bomb which killed the army chief of staff hours earlier. No-one has been prosecuted.