Camila nodded. She was clutching her hands together, her knuckles white from the pressure. “This was when the MTA still issued student passes for the subway. Do you remember those?”

Larkin did, not that he’d ridden the subway alone to and from school. That was far too pedestrian for his parents. “1997 was the year the MTA rolled out MetroCards for students.”

“Only the students who took the bus had the new cards. The ones who rode the subway didn’t get theirs until the fall,” Camila corrected. “You’re wondering why I remember this.”

Larkin waited.

“The student-issued MetroCard worked until 8:30 p.m. But the passes were only good until seven o’clock. The Center closed at 8:00 p.m., so the final duty of the mentors was to walk the students to the nearby stations and get the kids through the turnstile. The Center was preparing to save a lot of money come fall, since students would be able to get home on their free cards. But a lot of mentors—Marco included—worried that the time discrepancy would encourage those boys and girls to cruise the system and not go home.”

“Where is the Center located.”

Camila replied, “It’s long gone. It had donors, but mostly it was subsidized by the city. And in 2007, the city wanted to save money. It didn’t survive the recession.” She added after a breath, “Fifty-Fifth, between Eighth and Ninth.”

“And which station did Marco walk his students to in the evening.”

Camila raised a penciled-in eyebrow. That singular shift in her expression suggested satisfaction, approval, in the direction of Larkin’s thought process. “Fifty-Seventh Street. When it was the Q. The kids took it into Brooklyn.”

Larkin laid out a mental map of the current subway system, then overlaid it with his best approximation of how it stood in 1997, although he was aware there was room for error, as this was five years before HSAM changed everything he knew and understood about his own memory. Larkin asked, “Marco grew up in this apartment.”

“Yes, sir.”

“He would have taken the A home after work.”

“That’s right,” Camila answered. “He’d see the kids to Fifty-Seventh and then walk to the A at Columbus Circle. He rode it to 207th Street.”

“It wasn’t the responsibility of mentors to wait on the platform with students,” Larkin asked.

Camila shook her head curtly.

“And so why was Marco pushed in front of an uptown Q when his students rode the downtown and he took a different train located five blocks away.”

“That’s a good question, Detective,” Camila said neutrally. “One that I’ve been asking for twenty-three years.”

CHAPTER SIX

Larkin stood in the open doorway of the bedroom at the end of the hall, his gloved hand still resting on the tarnished doorknob.

He had been in homes like this, in rooms like this.