Around 1000 people attended the funeral of Arafat on Friday, one of the strongmen of Gaza and a cousin of the late Palestinian leader Yasser Arafat, at the main mosque in Gaza City.
The kidnapped son of murdered ex-security chief Arafat was released early on Friday.
He was seen entering the office of Palestinian leader Mahmoud Abbas in Gaza City, accompanied by Palestinian officials.
Mussa Arafat was killed when dozens of armed men stormed his house in Gaza City early on Wednesday. His son, Manhal, was abducted.
A masked man saying he represents the Popular Resistance Committees, a renegade group, reaffirmed responsibility for the killing and kidnapping after leaders of the group distanced themselves from the acts.
According to Aljazeera's correspondent in Gaza, Wail al-Dahduh, al-Nasir Salah al-Din Brigades has not explained the contradiction in its statements after it previously denied any role in the killing.
Manhal Arafat (R), son of Mussa
Arafat, after his release
The group first claimed responsibility for the assassination and abduction, then denied it, and later reconfirmed its responsibility, he said.
Neither the group nor the Palestinian Authority has issued any statements to explain these flip-flops.
But sources have told Aljazeera that al-Nasir Salah al-Din Brigades' contradictory stands could perhaps be explained by the presence of Major-General Mustafa al-Buhairi, head of the Egyptian security delegation, in Gaza.
Al-Buhairi's intervention may have led to multiple views within al-Nasir Salah al-Din Brigades, given the importance of his role as a mediator, al-Dahduh said quoting the sources.
Arafat, a relative of the late leader Yasser Arafat, was implicated in alleged corruption and was fired by Abbas.
However, his killing was seen as a direct challenge to the Palestinian government, which has pledged to stop renegade armed groups from acting with impunity in Gaza, before Israel's handover of the territory to Palestinian control next week.
Abbas has pledged to hunt down the killers.