WASHINGTON — The Chicago man with roots in Pakistan who was arrested two months ago for planning to attack a Danish newspaper now faces the much more serious charge that he was deeply involved in planning the 2008 massacre in India that killed more than 150 people, according to court documents filed by the Justice Department.

Court documents charge that David Coleman Headley, 49, an American citizen who is the son of a former Pakistani diplomat and a Philadelphia socialite, conducted extensive surveillance of targets in Mumbai, India, for more than two years prior to the attacks by the terrorist group called Lakshar-e-Taiba, which is based in Pakistan.

Six Americans were among the dead in the attacks on a Mumbai train station, the Oberoi and Taj Mahal hotels and other sites.

He has been charged with conspiracy to murder and maim in a foreign country, and material support of terrorism. Federal officials said the most serious charges, conspiring to carry out bombings that resulted in deaths, carry possible sentences of death or life in prison.

The Justice Department said that Mr. Headley, who is cooperating with the government’s investigation, spent several years and considerable effort on behalf of the plotters, attended training by the group in Pakistan, videotaped targets and briefed the other conspirators on how to carry out the attack on India’s largest city.

Mr. Headley took boat trips in and around Mumbai harbor in the spring of 2008, videotaping potential landing sites for the attackers, who would arrive by sea, the court documents charge. The attackers traveled from Karachi, Pakistan, hijacked an Indian fishing trawler, killed its captain, and then used a small boat to go ashore. The masked men used assault rifles and grenades in their deadly onslaught.

Mr. Headley also scouted out other potential targets in Mumbai and elsewhere in India that were not attacked, including the National Defense College in Delhi.

Mr. Headley, a resident of Chicago with a criminal record for smuggling drugs to the United States from Pakistan, was arrested in October with a Pakistani-born businessman, Tahawwur Rana, 45, who runs several businesses in Chicago and Toronto. Mr. Rana and Mr. Headley, who have known each other since attending an elite Pakistani military high school, were charged with plotting an attack against Jyllands-Posten, a Danish newspaper that published a series of cartoons depicting the Prophet Muhammad.

Mr. Rana, a citizen of Canada, was not charged in the Mumbai attacks. But officials said the two men appeared to consult closely, and Mr. Headley posed as a representative of a company owned by Mr. Rana. In a bail hearing last week, Mr. Rana argued that he was duped by Mr. Headley.

The Justice Department also announced Monday it had filed charges against Abdur Rehman Hashim Syed, a retired major in the Pakistani army, with collaborating in the plot against the Danish newspaper.

“This investigation remains active and ongoing,” said Patrick J. Fitzgerald, the United States attorney for the northern district of Illinois.

David Kris, the assistant attorney general for national security, said, "This case serves as a reminder that the terrorist threat is global in nature and requires constant vigilance at home and abroad."

Arrested on Oct. 3 at O’Hare airport in Chicago as he was boarding a plane on the first leg of a trip to Pakistan, Mr. Headley was officially charged a few weeks later with plotting to attack employees of a Danish newspaper that in 2005 published cartoons of the Prophet Muhammad that offended many Muslims.

Federal authorities said at the time that Mr. Headley told F.B.I. agents that he had initially targeted a building occupied by the Danish newspaper, Morgenavisen Jyllands-Posten in Copenhagen, but later proposed killing the paper’s cartoonist and cultural editor instead.

Officials said they regarded the case as significant because Mr. Headley traveled to Pakistan and consulted closely with three Pakistani men who belonged to Harakat-ul Jihad Islami, a terrorist group affiliated with Al Qaeda. The officials said Mr. Headley reported to Ilya Kashmiri, the operational leader of the terrorist group, who is based in a tribal region of northwest Pakistan.

When he was arrested, Mr. Headley was carrying about a dozen videotapes of the Danish newspaper office and surrounding areas that he was going to deliver to other conspirators in Pakistan, federal officials said. They said he had made the videotapes during several visits to Copenhagen in 2009.

Mr. Headley (or Daood Gilani, the name he was given at birth) is a man who has been pulled in different directions almost from the moment he was born. Even his eyes — one brown, one green — seem to symbolize the contradictions in his life.

Mr. Headley was born in Washington, where his Pakistani father and American mother worked at the Pakistani Embassy, he as a diplomat and she as a secretary. Mr. Headley’s mother, Serrill, grew up in a fashionable suburb of Philadelphia, and the cultural differences between her and her husband were too vast for the marriage to survive after the family went to Pakistan.

Serrill Headley left her husband and her children and moved back to Philadelphia sometime in the early 1970s. She worked at various office jobs and borrowed enough money from a suitor to buy an old bar, which she named the Khyber Pass.

In the late 1970s, she brought her adolescent son to Philadelphia to live with her. “Daood was not immune to the pleasures of American adolescence,” a former Khyber Pass employee once recalled.

Nor, to judge from his own words, was he immune to the lure of Islamic fundamentalism. “Courage is, by and large, exclusive to the Muslim nation,” he told high school classmates in an e-mail message last February.

More chilling was an e-mail message he wrote defending the beheading of a Polish captive by the Taliban in Pakistan: “The best way for a man to die is with the sword.”