US national Kenneth Haywood, to whose Internet connection a 'threatening' e-mail sent prior to the Ahmedabad serial blasts was traced, returned to the city in the wee hours on Thursday.
He returned with his family from Arizona in the US to Mumbai around 0100 hrs, sources said.
Haywood left the country on August 17 despite a 'lookout' notice being issued against him at airports across the country by the Maharashtra Anti-Terrorism Squad (ATS).
The US national, who had undergone polygraph and brain mapping tests during investigation, was cleared of "doubt" by the ATS officials.
However, the officials had said they wanted to investigate Haywood's allegations that an ATS official had demanded a bribe from him to clear him in the case.