Investigations into the threatening email sent prior to the Ahmedabad serial blasts have revealed that it is unlikely someone hacked into the suspected American national's computer to send the message, police said on Monday.
"We asked some private consultants regarding the email and the general opinion was that it is unlikely that Ken Haywood's computer was hacked to send the message," Joint Commissioner of Police (Crime) Hemant Karkare said.
The use of the unsecured wireless Internet router at the American national's residence is suspected to have been used to send the email, he said.
The IP (internet protocol) address from which the email was sent to some media channels a few minutes prior to the Ahmedabad blasts was traced to the residence of Haywood, an American national residing in Navi Mumbai.
Investigators are hopeful of getting some clues from the interrogation of persons living in the same building as the American national, Karkare said.
"Most of the suspects we wanted to question were available," he said.
The Anti Terrorism Squad is still to receive the forensic laboratory reports of the 10 computers seized from the Navi Mumbai building in which the American national resides.
Enquiries were being made with suspects who were former cadres of the banned organisation Students Islamic Movement of India and other organisations, but no leads have emerged, Karkare said.
Also, there is no headway in investigations into the theft of the four cars which were used in the Ahmedabad blasts and found loaded with explosives in Surat, he added.