On Monday, July 26th, Anthony Barajas, 19, and Rylee Goodrich, 18, were both shot in the head at a theater in Corona, southern California, some 50 miles southeast of downtown Los Angeles, while watching The Forever Purge.
Workers at the cinema discovered them after the last showing of the night.
Mr Barajas was brought to a local hospital for treatment, while Ms Goodrich died at the spot.
Police confirmed on Saturday that the boy had died as a result of his injuries. The shooting looked to be random and unprovoked, according to officers.
On Friday, suspected gunman Joseph Jimenez, 20, appeared in Riverside County Superior Court after being charged with Ms Goodrich's murder and Mr Barajas' attempted murder. Officers are already working with prosecutors to add a second murder charge to the case.
Jimenez has yet to make a plea and is scheduled to return to court next week.
He's also been charged with a specific circumstance of lying in wait, which could lead to the death penalty if he's found guilty.
According to the Riverside Press-Enterprise, Mr Barajas was a high school honor student. According to NBC, he was known online as "itsanthonymichael," with almost a million TikTok followers and more than 50,000 Instagram followers.
Anthony's presence was a blessing to all who knew him, from his quick smile to his kind heart, his family stated in a statement.
Mr Barajas' GoFundMe page, which was set up to help cover medical costs while he remained on life support, has now raised more than $80,000 (about £57,500) in donations.