Tyler Brown appeared in in Cambridge District Court on Thursday, three days after prosecutors say he left two people with life-threatening injuries in a shooting incident on Memorial Drive.

The gunman was shot by a Massachusetts State Police officer and a former Marine, and was in a Boston hospital on Monday evening.

Known only as “John” in a Providence police affidavit, the source is being hailed by investigators as the key figure who gave law enforcement the details needed to determine who was behind the Brown shooting.

Boston is experiencing a lower number of homicides this year compared to last year. But for families affected by the violence, it's not enough. The Louis D. Brown Peace Institute hosts its 28th annual Mother’s Day Walk for Peace on Sunday.

Prosecutors said Crumbley and her husband ignored signs that their son, Ethan, was seriously troubled, bought him the gun he used and didn't take steps to prevent the 2021 Oxford High School shooting.

The suspect, a student at the school, died of what investigators believe is a self-inflicted gunshot wound.

The team at Boston University's CTE Center will look to see if repeated exposure to explosives while serving in the military could have contributed to the shooter's behavior.

A person opened fire Wednesday on the University of Nevada, Las Vegas campus. Police say the shooter was found dead.

A fierce debate continues about the extent of additional gun regulation, such as restricting where legal gun owners can carry.

Police said the shooting was contained and that patients are safe as of late Friday.