At St. Michael's Cemetery in Queens, those friends - about 20 old roommates, former co-workers and members of his Hindu temple - chanted as they bore his pale-blue coffin through the doors of the small chapel off the crematorium. One flicked holy water over the others as they placed incense, candles, puffed rice and bananas on paper plates around the raised coffin, reciting and singing Hindu prayers and mantras.
Sen, 46, was pushed from behind onto the tracks at the 40th Street-Lowery Street station around 8 p.m. Thursday. With no chance to defend himself or react, he was pinned under an incoming No. 7 train. On Saturday, the police arrested Erika Menendez, 31, who told investigators she had shoved Sen onto the tracks because she believed he was a Hindu or Muslim and wanted to retaliate for the attacks of Sept. 11, 2001.
Menendez was charged with second-degree murder as a hate crime. For years, according to friends and law enforcement officials, she had suffered from mental illness, receiving psychiatric treatment from at least two city hospitals. Her turbulent past included at least three arrests, two for violent outbursts.
No one at Sen's cremation ceremony publicly mentioned his attacker. As a few in the small crowd took photos, others busied themselves with lighting the votive candles. Adapting elements of a traditional Hindu send-off, several men walked in counterclockwise circles around their friend's coffin as they chanted the Hare Krishna, praying that Sen's soul would separate peacefully from his body. In preparation for the burning, a mourner set the bananas, puffed rice, leaves and other traditional offerings atop the flowers that blanketed Sen's body before pouring a jug of milk into the coffin.
A temple representative asked for a minute of silence.
"Forgive him," he said. "Pray for ... him, for peace in his soul."
With a final prayer, the mourners followed the coffin to the crematorium and chanted as it slid toward the flames.
Customarily, Hindu funeral rites are performed by the deceased's brother, son or other close relative alongside religious elders. But both of Sen's parents died more than a decade ago in India, where he was born and raised, and he had no siblings. Friends said he had fallen out with more distant relatives in India after his mother died several years after he arrived in New York, and was no longer in contact with them.
It was his lack of family ties in India that kept him in New York even after he failed to finish his doctorate in economics at New York University about 15 years ago, friends said. Though he had lost the scholarship that brought him here, he decided to stay in the country and found a job at a copy center in Greenwich Village, where he worked until quitting soon before he suffered a stroke in October 2011.
He was quiet, friends recalled, but generous with favors. People frequently asked him to fix their electronics, and he almost always could. He enjoyed movies - as many as three a day - American literature and Indian religious music, they remembered.
"You ask him 10 questions, you probably get two answers," said Mohammad Rahman, 34. "But any problem, he was the guy. He was a very talented and cool guy."
Sen had been a promising student, earning a master's degree with first-class honors in economics at one of India's most prestigious universities, Jawaharlal Nehru University in New Delhi. But his friends said that his mother's death and his failure to complete his Ph.D. propelled him into depression and sapped him of ambition.
After he recovered from his stroke, however, Sen decided to start a copy business of his own, relying on an initial investment from his oldest friend and former roommate, Sanjeeb Das. He called it Amsterdam Copy Center. And after years of shaking his head at his friends' urgings to marry and start a family, he had allowed his friends to begin looking for a wife for him among the Hindu Bengali community.
He felt he belonged in New York. "'I don't want to go back there,"' to India, one of his oldest friends, Ashim Dey, 48, recalled Sen telling him. "'You're the people who have to take care of me."'