The two were produced before a Magistrate's Court after the expiry of their police remand in the case related to Usmani's escape.
The court extended the custody of Usmani, an accused in 2008 Ahmedabad bomb blasts, and his nephew after Anti-Terrorism Squad (ATS) of Maharashtra Police said they have to conduct further investigation into the September episode.
Usmani was re-captured from outside a railway station in Uttar Pradesh while he was preparing to cross-over to Nepal on October 27, over a month after he escaped from a Mumbai Court.
Usmani later met Javed (19), who resided in suburban Dharavi. Javed, son of Usmani's sister, arranged Rs 5,000 and the duo left for Uttar Pradesh via Gujarat and Madhya Pradesh.
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According to the police, Usmani was involved in stealing four cars which were used to transport explosives to Ahmedabad and Surat. He was also charged with planting bombs.
Over two dozen unexploded bombs were found at different locations in Surat between July 28 and 30.