He is retired from the post and presently in charge of the newly-set up Raksha University.
Mathur was head of the state CID Crime department which was heading the investigation into the case before the Supreme Court handed it over to the Central Bureau of Investigation.
Mathur had been issued summons to appear before the CBI.
The Gujarat Anti-Terrorism Squad has been accused of killing Sheikh near Ahmedabad on grounds that he was a Lashkar-e-Taiba operative in a staged shootout on Nov 26, 2005.
His wife Kauser-Bi was also allegedly killed in a fake encounter later as was an witness to her husband's killing.