New Delhi, India (CNN) -- Gunmen shot dead a lawyer representing a man accused of helping the Mumbai, India, attackers who killed 164 people in November 2008, an official said Thursday.
Shahid Azmi was shot by three attackers, police believe.
Azmi represented Fahim Ansari, who was accused of helping to plan the Mumbai siege.
Public prosecutor Ujjwal Nikam, a key lawyer in the Mumbai case, confirmed Azmi's death.
Police are investigating to determine the motive, they said.
Ten men launched a carefully planned attack on buildings such as the Taj Mahal Palace and Tower and Oberoi-Trident hotels, Mumbai's historic Victoria Terminus train station and the Jewish cultural center, Chabad House, starting on November 26, 2008. It lasted three days.
Indian forces killed nine suspects.
The only surviving suspect, Pakistani Mohammed Ajmal Kasab, 21, was formally charged in November with attempted murder and damage to public property, Nikam said.
Ansari -- the man whose lawyer was killed -- and Sabahuddin Ahmed were charged the same day with helping to plan the attacks, according to the prosecutor.
Kasab confessed in July, but recanted in December, Nikam said.
Prosecutors said Kasab's guilty plea was an attempt to deflect attention from his alleged handlers in Pakistan. When he recanted, they said the confession was Kasab's way of creating drama in the courtroom.
The next hearing in the case is set for March 9.
The Indian government blamed the attacks on Lashkar-e-Tayyiba, a Pakistan-based terror group allied with al Qaeda. Authorities said Kasab was trained by the organization, which was banned in Pakistan in 2002 after an attack on India's parliament. The group denied responsibility.