Seth Jones, a RAND Corp. political scientist, agrees Headley must have provided useful insight for American intelligence, especially about how Pakistani intelligence agents allegedly reach out to people like Headley.
"From my perspective, this was pretty detailed information about one ISI contact (Headley) with one handler, Iqbal," said Jones. But he added Pakistani intelligence would have been careful not to reveal too much to Headley, saying, "They didn't trust him either."
For his cooperation and guilty plea to 12 counts, Headley secured both a promise that he would not face the death penalty and would not be extradited to India. Late last year, India secretly hanged the lone gunman who survived the Mumbai attack, Mohammed Ajmal Kasab.
The 12 counts Headley pleaded guilty to included conspiracy to commit murder in India and aiding and abetting in the murder of six Americans, who included Americans Alan Scherr and his 13-year-old daughter, Naomi.
Scherr and her family were in India for a two-week spiritual retreat and were staying at the Oberoi Trident Hotel, one of the sites that came under assault.
After the attack, Scherr helped start an organization called the One Life Alliance, which seeks to work against terrorism by promoting understanding and respect for the sacredness of life.
"This is how I am surviving this event, which erased life as I knew it," she wrote in an email from Mumbai, where she continues to travel to for charity work.
Another survivor, Andreina Varagona, described in a presentencing filing dining with the Scherrs at the hotel restaurant when gunmen burst in. Bullets tore apart the room as they dove under a table, the girl screaming.
"I suddenly felt the warm spray of blood on my face and in my hair. ... Naomi's screams had stopped too, and I saw her lying lifeless beside (her father)," she recounted. "They'd both been shot dead."