A security review was under way after Sunday's shooting rampage by Ali Hassan Abu-Kamal, 69, on the skyscraper's observation deck which left two dead and others wounded. Abu-Kamal shot himself in the head and later died in hospital. The dead victim was identified as 27-year-old Chris Burmeister, a member of a Danish rock band.
The gunman's daughter, Linda Abu-Samra, said she could not believe her father, an English teacher, would resort to violence. "I'm in shock. I can't believe my father carried out this act," she said.
The gunman's son-in-law, Marwan Abu-Samra, said he had no ties to Palestinian militant groups. Mr Abu-Samra said Abu-Kamal planned to invest his savings in the US. But he called home on Sunday to say he had financial problems and could not send tuition money to one of his sons who is studying civil engineering in Russia.
The mayor of New York, Rudolph Giuliani, sought to divert some of the responsibility on to the state of Florida, where Kamal apparently purchased the semi-automatic gun used in the attack. Florida has gun laws that allow foreigners to buy weapons in the state.