A 21-year-old Bergen County man told police that he chatted with a young woman on social media in the week leading up to a group "hang-out" that ended with the 19-year-old female's death — which happened after he choked her during sex — authorities allege.

Michael Gaffney is charged with reckless manslaughter after the Nov. 2 death of Francis Victoria Garcia.

Hackensack Police responded to a 911 call early Saturday, after 2 a.m., to Garcia's vehicle parked in the garage adjacent to an apartment complex at 140 Prospect Ave., according to the Bergen County Prosecutor's Office.

According to the affidavit of probable cause filed by police, Gaffney said Garcia already had two mutual friends in her car when she picked him up at his home Friday, Nov. 1, around 5 p.m.

Gaffney told police that the group drove to another friend's residence at the Prospect Avenue complex and they all went inside, the affidavit says. After that, the affidavit says Gaffney told officers, he and Garcia went back out to her car, where they had sex for about 20 minutes, during which he put his hands around her neck.

Garcia then lost consciousness, at which point Gaffney contacted the friends who had stayed inside the apartment, telling them that Garcia was not breathing, the affidavit says he told police.

One of the male friends then came out to the vehicle and saw that Garcia's lips were purple, but said he still felt air escaping her nose, the affidavit says Gaffney told police.

Garcia was pronounced dead just before 3 a.m. at a local hospital.

The same police affidavit said Garcia had a blood-alcohol level of .256 at the time of her death, as confirmed by the medical examiner.

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