The substance, which investigators later determined was non-hazardous, was found in a letter addressed to DA Alvin Bragg. NBC News' Laura Jarrett provides more details. » Subscribe to MSNBC: http://on.msnbc.com/SubscribeTomsnbc Follow MSNBC Show Blogs MaddowBlog: https://www.msnbc.com/maddowblog ReidOut Blog: https://www.msnbc.com/reidoutblog MSNBC delivers breaking news, in-depth analysis of politics headlines, as well as commentary and informed perspectives. Find video clips and segments from The Rachel Maddow Show, Morning Joe, The Beat with Ari Melber, Deadline: White House, The ReidOut, All In, Last Word, 11th Hour, and Alex Wagner who brings her breadth of reporting experience to MSNBC primetime. Watch “Alex Wagner Tonight” Tuesday through Friday at 9pm Eastern. Connect with MSNBC Online Visit msnbc.com: http://on.msnbc.com/Readmsnbc Subscribe to the MSNBC Daily Newsletter: MSNBC.com/NewslettersYouTube Find MSNBC on Facebook: http://on.msnbc.com/Likemsnbc Follow MSNBC on Twitter: http://on.msnbc.com/Followmsnbc Follow MSNBC on Instagram: http://on.msnbc.com/Instamsnbc #AlvinBragg #Crime #MSNBC