Updated

New York City police believe a Ukrainian immigrant involved in a bitter custody dispute tossed his 3-year-old son from the roof of a Manhattan apartment building before jumping to his own death Sunday.

The New York Post reported that Dmitriy Kanarikov, 35, of Brooklyn, was supposed to hand over son Kirill to his estranged wife at a Manhattan police precinct house.

Instead, authorities say Kanarikov went to the top of the 52-story South Park Tower on West 60th Street, near Columbus Circle and Lincoln Center, and across from St. Luke's Roosevelt Hospital.

The body of Kirill Kanarikov was found on a sixth-floor landing of a John Jay College building next door to the apartment tower. The boy's father's body was found on the fourth floor of the same structure.

Police believe that Dmitriy Kanarikov threw his son to his death before jumping because of the distance between their bodies, as well as the fact that the man was found closer to the apartment building, which indicated a more direct drop.

It is not clear how Kanarikov got into the building, since he did not live there.

Luis Ortiz told the Post that he was at St. Luke's Roosevelt Hospital when paramedics rushed the boy there and that they were pumping his chest and working on him.

"You could tell he was slipping away," Ortiz told the newspaper. "They said the father was up there, but they didn't bring anyone else in. It was just heartbreaking. I have two kids of my own. They tried to do the best they could."

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