Word on reddit (not confirmed, but the pieces of evidence seem credible), is the shooter shot a woman in Baltimore, fled to NYC and posted this.

http://i.imgur.com/mqhUk9m.jpg


This is another pic from his instagram today.

http://photos-h.ak.instagram.com/hphotos-ak-xaf1/t51.2885-15/10881787_758814077506279_217118118_n.jpg

And it matches the clothing and shoes from the crime scene photo

https://thenypost.files.wordpress.com/2014/12/122014_brooklyn_cops_shotpm-1.jpg