Why did a man who helped kill more than 160 men, women and children get a 35-year sentence?
There are answers but not everyone likes them.
Headley had no mercy for those who were attacked but received mercy from a very hesitant district judge in Chicago.
It was Headley's immediate cooperation with the FBI and federal prosecutors and then his complete testimony that resulted in a life-saving deal.
The sentencing of Chicagoan Headley was the top story in India Thursday and Indian news crews were at the Dirksen Federal Building.
"People in India have been outraged from the time he was able to strike a plea bargain with the American government," India Times Now Reporter Shalini Parekh said. "The fact that he was able to escape the death sentence and also the fact that he cannot be extradited to India, Pakistan or Denmark has been a cause of ongoing concern."
Headley's plea bargain prohibits him from being executed and from ever being extradited to India.
He cannot be extradited to Denmark either even though he pled guilty to a terror plot against a Copenhagen newspaper that had offended Muslims.
"What we want the people in India to know is that we have expended years of our lives and of hundreds of others agents and prosecutors investigating a crime that happened on their soil in the hopes of bringing some justice to the people of India and the point of this exercise is to bring other witnesses to help bring terrorists to justice," acting U.S. attorney Gary Shapiro said.
Prosecutors said they wrestled with the seriousness of Headley's crime and the value of his cooperation.
"Mr. Headley is a terrorist," U.S. District Judge Harry Leinenweber said in court. "An easy sentence would be death for such a man."
His sentence won't deter future terrorists but society needs protection from Headley, according to Leinenweber.
"I don't have any faith in Mr. Headley when he says he's a changed person and believes in the American way of life," he said.
Headley submitted a letter asking for clemency. His lawyers wanted far less than the 35 years he received.
"We believe that Mr. Headely's cooperation, which has gone on for the last three years, we thought it might have given the judge reason to reduce the sentence that he gave but we understand what Judge Leinenweber said at the hearing and we don't think there is anything else we can add to that," Headley attorney Jon Theis said.
Indian media asked: was Headley given leniency because he once worked as a federal drug informant? And when were U.S. officials aware of headley's terrorist ties?
Regardless of his future intelligence value, there seems to be little acceptance in India that 35 years is adequate punishment for the Mumbai carnage.
New Delhi has to tread carefully. The U.S. is its number one ally in the war on terror and as one official said, they can't complain too loudly about the Chicago decision.