A Portuguese banker who managed accounts allegedly used by Africa’s richest woman to embezzle Angolan state funds has been found dead in his Lisbon flat.

Nuno Ribiero da Cunha was found hanging in the garage of his home on Tuesday evening hours after prosecutors investigating the business dealings of Isabel dos Santos, the daughter of Angola’s former president, said they wanted to question him under caution.

Police in the Portuguese capital said there were strong indications that Mr Ribiero da Cunha, who was 45, had committed suicide. Earlier this month he was found bleeding from several knife wounds to his wrists and stomach by a household employee in one of his holiday homes on the coast south of Lisbon.

The police were still investigating the circumstances of that incident, with both suicide and attempted murder among their hypotheses, and Portuguese newspaper Observador reporting that investigators were “investigating the bank manager’s mobile phone to try to understand if he was being coerced”.

Other Portuguese media quoted sources close to the banker’s family as saying that Mr Ribeiro da Cunha had been depressed recently, and the national director of Portugal’s judicial police force, Luís Neve, said “everything suggests that no third party was involved” in the banker’s death.