A TikTok teen charged with murder. A defense team requests evidence testing. Plus, interrogation tactics.

17 year old Sarah Grace Patrick is accused of gunning down her mother and stepfather in Georgia. The defense team of the man accused of killing UNC Chapel Hill student Faith Hedgepeth in 2012 has filed motions that raise new questions about crime scene evidence. Updates on Florida matriarch Donna Adelson's trial and former MLB pitcher Dan Serafini. Plus, an inside look at police interrogations and the tactics investigators use. Find out more about the cases covered each week here: www.datelinetruecrimeweekly.com To learn more about Dateline LIVE in Nashville on Sept. 28, and to get tickets, go here: https://www.nbcnews.com/dateline-event