How to stage a terror attack and get away with it!

This video was submitted to us at Independent Media Solidarity(IMS) by 'New Liberty Times'. To my knowledge its the only video he made.
4:18 , The beginning of Thorndike's explosion photographs were taken beginning 2-3 seconds after the detonation.Upper center in the middle of the smoke is Kyle Larrow (dark hair, torn clothing) and he almost immediately flees the scene.Which is a little odd considering everyone else in the blast area has been knocked down but somehow he's managed to pick himself up and start to run away.And manages to jump over a fallen lady and avoid bumping into other people as he flees amid the smoke and chaos. Here is a link to the complete set of Thorndike - https://imgur.com/a/Cza6V
The explosion was at marathon clock time 4:09:43, we don't know where he ran to but here is a photo of him about to return over 3 minutes later - https://www.flickr.com/photos/hahatango/8652900625/in/album-72157633252445135/
Double click on the photo to enlarge, right and above the patio is a man in a grey sweatshirt standing with his hands on his head, directly behind him is a grey haired man and that is Kyle's head just behind that man.
Over 4 minutes later he's back on scene - https://www.flickr.com/photos/hahatango/8654010710/in/album-72157633252445135/
He hangs out before inexplicably running about two blocks away to Boylston and Fairfield. I'll link that in a moment.You should know by this time the streets between where Kyle ended his run and site one is filled with dozens upon dozens of emergency personel and vehicles.
Video link showing Kyle actually running - https://youtu.be/yq_nJl56LSg?t=440
Photo link showing Kyle at Fairfield - https://www.flickr.com/photos/kenshinokubo/8653410158/in/album-72157633255956194/