San Francisco police arrested and charged a man with murder on Monday for allegedly killing a seven-month-old baby who was placed in his care, prosecutors said.

Authorities charged the suspect, Joseph William, with murder and assault on a child causing death, the San Francisco District Attorney’s Office said. They said the man was babysitting the victim they only identified as Baby S., on April 20 before the crime occurred.

Child Murder

Later that day, Williams brought the baby to the hospital to be treated. Medical professionals determined the child died of traumatic head injuries caused by blunt force. Prosecutors said the victim was not related to the suspect.

The DA’s office revealed Williams was previously arrested twice for domestic violence against a girlfriend who wasn’t the mother of the victim. Authorities did not charge him after the woman told police she was the one who started the fights. The first is when she broke into Williams’ apartment, the Associated Press reported.

“We believe the available facts of these two cases supported the decision to not move forward with charges but that is not enough. In light of this tragedy, we will be reviewing all policies related to charging domestic violence crimes, including discussions with our law enforcement partners to ensure we are all using best practices to obtain admissible evidence and to support victims,” said the DA’s office.