Landau recently took part in an environmental convention in Abu-Dhabi. In an interview with Al-Jazeera al-Zahar said it was possible the assassins had come with him and entered Dubai under assumed identities, using false passports.
"A week before the assassination Uzi Landau visited the emirates and he may have had people traveling with him under false names and additional citizenships," he said.
To other news agencies al-Zahar repeated that "the Zionist occupation wants to change the rules of the game" by assassinating al-Mabhouh, and that Hamas had every right to defend itself.
"We will consider all of the positive and negative outcomes of response for the crime of assassination," al-Zahar explained.
"We can hurt the occupation within the borders of occupied Palestine or without. This is in our hands. We will choose the best thing for us, our people, and our ties with other Arab and Muslim countries."
He added that Hamas was in touch with United Arab Emirates security forces in charge of the investigation. Israel has not claimed responsibility for the killing.
"The Israeli side is accustomed never to declare the crimes it commits, because it does not want to commit itself to diplomatic obligations or international law," al-Zahar said.
He called on Arab countries sustaining diplomatic relations with Israel to respond to the incident in order to keep "the region from becoming an assassination field".
A senior source in Dubai said Friday afternoon that local police had managed to identify the men suspected of assassinating al-Mabhouh, who was responsible for the kidnapping and killing of IDF soldiers Aviv Sasportas and Ilan Saadon.
According to the official, the police were conducting a manhunt for the suspects, who he said have European passports, and had even appealed to the Interpol for help. He added, however, that the two had apparently left the emirate.