Daylan Mallard is accused of attacking Bruce at a bus stop on North 12th Street in what witnesses described as an unprovoked assault that ended in beating and strangulation.

According to the complaint, a witness identified by the initials LSM told police she was waiting at the bus stop when a stranger approached and said, "That old man was just waiting at the bus stop and this man walked up to him and charged him for no reason."

The witness said Mallard put Bruce in a headlock and punched him repeatedly as Bruce appeared unable to defend himself, bleeding from his nose and mouth. She told investigators Mallard threatened her as well, saying, "I'm gonna come after you too, once I'm done with him." She said Bruce urged her to "go" while struggling to breathe.

The witness also told police she saw Mallard drag Bruce by a lanyard around his neck and keep hitting him after he stopped moving.

Security video described in the complaint showed a person believed to be the suspect punching someone on the ground, walking away, then returning to attack again. The video also showed bystanders gathering before officers arrived.

Three people who had been at a nearby restaurant went to help after a woman alerted them to the attack, the complaint states. One of them told police he saw Mallard pulling on the lanyard around Bruce's neck while pressing down on him with his feet. The men yelled at Mallard to stop, and one pulled the lanyard away, according to the complaint. One of the men began CPR on Bruce.

Police arrived to find Bruce unconscious and not breathing. Officers and firefighters attempted to revive him, but he died.

An autopsy found Bruce suffered blunt force injuries to his head and neck, as well as injuries consistent with manual strangulation. The medical examiner determined the cause of death was multiple blunt force injuries and manual strangulation, and ruled the death a homicide.

Mallard faces a Class A felony charge, which carries a mandatory life sentence if he is convicted.

Bruce's death has shaken colleagues and families connected to Milwaukee Public Schools, where he worked as a special education teacher. Family and friends held a vigil in his memory following the attack.

The case remains under investigation, and court proceedings are expected to continue in the coming weeks.