NEW YORK (CBSNewYork/AP) – A timeline of events in the hours before and moments after two New York Police Department officers were killed in their cruiser Saturday by Ismaaiyl Brinsley, a 28-year-old man who vowed online to shoot two “pigs” in retaliation for the police chokehold death of Eric Garner.

At a news conference Monday afternoon, police asked the public for help in filling a 2 hour and 30 minute gap in their timeline of Brinsley’s actions.

Police also released surveillance video of Brinsley before the shooting (seen in the video player above), hoping someone will recognize him and come forward with information.

(Credit: NYPD)

(Credit: NYPD)

___

5:51 a.m. – Baltimore County police are dispatched to Brinsley’s ex-girlfriend’s home in the Baltimore suburb of Owings Mills, Maryland. Brinsley had shot the 29-year-old woman in the stomach and fled with her phone. She’s expected to survive.

6:05 a.m. – Brinsley calls his ex-girlfriend’s mother and tells her he shot her daughter by accident and hopes she will survive.

6:35 a.m. – Brinsley boards a bus to New York City.

10:50 a.m. – The bus arrives in Manhattan.

12:07 p.m. – Brinsley discards his ex-girlfriend’s phone in Brooklyn, hiding it behind a radiator in a small shopping mall across from the Barclays Center, police sources tell CBS News.

1:30 p.m. – Police in Baltimore County discover Brinsley has made posts from his Instagram account that threaten to kill officers. They determine the posts are being made from Brooklyn. Police sources tell CBS News at this point, police first became aware that he had left his cell phone at his ex-girlfriend’s house and took  her phone.

2:10 p.m. – Police in Baltimore County call the NYPD, advising officers that the phone of a suspect in the Owings Mills shooting is pinging in Brooklyn. The two police departments discuss the Instagram posts during the call, and the NYPD officer asks that a wanted poster of Brinsley be faxed to the NYPD with information about Brinsley.

2:45 p.m. – Brinsley walks up to two people on the street in the Bedford-Stuyvesant section of Brooklyn, asks them to follow him on Instagram and tells them, “Watch what I’m going to do.”

2:46 p.m. – Baltimore County Police Department faxes a wanted poster of Brinsley to the NYPD with information about him.

2:47 p.m. – Brinsley approaches the passenger window of a marked police car and opens fire, striking Officers Rafael Ramos and Wenjian Liu in the head, killing them. He takes off running as officers pursue him to a nearby subway station, where he shoots himself in the head.

2:49 p.m. – The Baltimore County Police Department sends a teletype with the same information contained on the wanted poster to the NYPD’s real-crime center at police headquarters.

You Might Also Be Interested In:

[display-posts category=”news” wrapper=”ul” posts_per_page=”4″]

(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)