(CNN) -- A federal grand jury indicted four more people on charges involving the 2008 terrorist attacks in Mumbai, India, that left more than 160 people dead.
The case is linked to David Headley, who pleaded guilty last year to all 12 charges against him in connection with the four-day siege on India's financial capital and a plot to attack a Danish newspaper.
Headley was not charged in the new indictment, but his role is spelled out in detail throughout the charges that describe an extended plot involving years of surveillance, setting up a front organization to hide activities, getting money to pay for planning, and communications between some of the suspects and the Mumbai attackers as the siege took place.
The new indictment included charges of aiding and abetting the murder of U.S. citizens in India and conspiracy to bomb public places in India. Both carry a maximum penalty of life in prison or death.
In addition, some or all of the suspects in the new indictment were charged with conspiracy to murder and maim in India, conspiracy to provide material support to terrorism in India, conspiracy to murder and maim in Denmark and others that carry a maximum penalty of life in prison.
Named in the new indictment were Ilyas Kahmiri, Tahawwur Hussain Rana, Abdur Rehman Hashim Syed, Sajid Mir, Abu Qahafa, Mazhar Iqbal and an unidentified man referred to by the alias of Major Iqbal.
Rana, a Canadian citizen and Chicago resident, is the only suspect in U.S. custody. Rana, Kahmiri and Syed were named in previous indictments that charged Headley, who also lived in Chicago. The other suspects were all believed to live in Pakistan.
Kahmiri is a leader of the Pakistani terrorist group Harakat ul Jihad al Islami, or the Islamic Struggle Movement, and has close contact with a known al Qaeda leader, according to the indictment.
The four new suspects named in Monday's indictment were Mir, Qahafa, Iqbal and the unidentified man referred to by his alias.
Headley, the son of an American mother and Pakistani father, was accused of extensive involvement in planning the devastating attacks on hotels in Mumbai, which the Indian government says were carried out by the Pakistan-based terrorist group Lashkar-e-Tayyiba. At least six Americans were among the dead.
Headley initially pleaded not guilty to the charges, then changed his plea as part of a deal with the government to cooperate with investigators in exchange for a maximum possible sentence of life in prison. By pleading guilty, he also gave up his right to appeal. Headley's actual sentence will depend on how much he cooperates with authorities.
The new indictment Monday charged that Headley, working in connection with the other suspects, scouted targets in Mumbai for more than two years to set up the November 2008 attacks. It included details of what happened that day, saying that "during the course of attacks in Mumbai, the attackers were in telephonic contact with defendants Sajid Mir, Abu Qahafa and Mazhar Iqbal, all of whom were then located in Pakistan."
"More specifically, during the course of the attacks, the attackers were advised to, among other actions, kill hostages, set fires and throw grenades," the indictment said. "Sajid Mir also sought to arrange the release of a hostage in exchange for the release of a captured attacker."
It also accused Mir of working with Headley to plan a terrorist attack on a Danish newspaper, which was never carried out. The newspaper became the target of Muslim fury in 2005 after it published cartoons depicting the Prophet Mohammed in a manner offensive to Muslims.