Heyward's death follows the OD death of of Odom's friend Jamie Sangouthai, which left Odom devastated.
One of the sources in the Us story says Odom is "beside himself" with grief over this latest tragic loss of life.
Heyward's final Instagram post was a 2007 image of Odom with a group of friends including himself and Sanghouthai. Heyward wrote, "#RIP To my big brother Jamie who always brought light into any room he walked into and laughter as well at all times J you will always be missed. Family for life. #BandofBrothers #tbt"