A 3-year-old boy is believed to be the person who fatally shot his 2-year-old brother in a Brooklyn Park apartment, authorities said Monday.

The 2-year-old was shot Thursday morning at the Huntington Place Apartments in the 5800 block of 73rd Avenue and died Saturday, said Deputy Police Chief Mark Bruley.

The 20-year-old mother and 57-year-old grandmother of the two boys were jailed on suspicion of covering up the crime after the fact and then released "so they could say their final goodbyes to the child" while he was on life support at the hospital, Bruley said.

The release also allowed the mother to sign off on having her 2-year-old's organs made available for donation, the deputy chief said.

"We don't consider them a danger to society" or a flight risk, Bruley said. "They will get charged. I just felt like on the humanity side … it seemed like the right thing to do."

Bruley said the 3-year-old, who turns 4 in less than two months, was "right there" with his little brother, and "it is most likely that the [older] brother discharged the firearm. We don't see that the 2-year-old would have the capacity to do it."

Also in the apartment at the time was the mother's 20-year-old boyfriend. He surrendered to police Saturday on suspicion of child endangerment. He's also been released ahead of charges.

People in the apartment spoke about someone with the initials B.D. fleeing from the scene. Police later determined that B.D. "does not exist" and that account has been recanted, Bruley said.

Charges could come Monday or Tuesday, Bruley said. The Star Tribune generally does not identify suspects before they are charged.

The identity of the 2-year-old will be released by the Hennepin County Medical Examiner's Office.