Fadi Mohammad al-Batsh, 35, was killed in a drive-by shooting on Saturday, according to Malaysian authorities.
He was walking from his highrise apartment to dawn prayers at a local mosque in the Kuala Lumpur suburb of Gombak when he was shot by two gunmen riding a motorcycle, officials added.
At the crime scene, police markers indicated 14 bullets had been sprayed at the victim, some of them hitting a wall. An iron grill hit by a bullet was dented.
Malaysian Home Minister Ahmad Zahid Hamidi, was quoted by the state-run Bernama news agency as saying Batsh was "an electrical engineer and an expert at making rockets".
Kuala Lumpur police chief Mazlan Lazim said the investigation was ongoing.
"We are investigating all angles. I have to investigate very carefully and deeply. This is an international issue," Mazlan said Sunday.
He said the autopsy was being carried out at a hospital after which the body would be released to the family.
In a statement from the Hamas-ruled Gaza Strip, the victim's family said: "We accuse the Mossad of being behind the assassination."
The Islamist Palestinian movement said Batsh, a research scientist specialising in energy issues, was one of its members.
Mohammad Shedad, 17, a student and a relative of the victim, also blamed Mossad for the killing.
"It is definitely the work of Mossad. Fadi is a very clever person, anyone who is clever is a threat to Israel," he told AFP outside the victim's Malaysian home.
"Fadi is a Hamas member and knows how to make rockets. So (Israel) think he is dangerous."
Batsh leaves behind a wife and three young children. He had lived in Malaysia for the past 10 years. Ahmad Abu Bakar, 33, a foreign student studying in Malaysia, said he had known the victim for two years.
"He is friendly and he preaches good things. He never preached any hatred. I am shocked by the killing," he said.
Robert Anthony, 56, a security guard at a Chinese primary school near the scene, said he heard the shots ring out but assumed they were "firecrackers". //AFP