On a warm June evening in Camden, five teens and preteens followed a homeless man into an alley behind the PATCO tracks, according to court documents unsealed Friday. The group exited the alley minutes later, leaving their victim bloodied and brutalized after a fatal beating with pieces of concrete.

Those five suspects, one as young as 12, were arrested in the weeks after. One of them, Tresjure Knight, bragged about the attack to her friends, texting them that she had “caught [her] first body,” according to the affidavit of probable cause in her arrest.

Though she has been in custody since June, Knight, 17, is now being charged as an adult for first-degree murder, conspiracy to commit aggravated assault, and desecration of human remains, prosecutors said Friday.

Knight, of Pennsville, Salem County, also filmed the attack and its aftermath, taunting Bobby J. Hill Jr., a homeless man well-known to those working in outreach in the city, as he lay prone saying, “This is what we doin ... in all 2020,” the affidavit said.

» READ MORE: Teens charged in beating death of homeless man in Camden

The upgrading of those charges out of juvenile court provided the first detailed look into the specifics of Hill’s death.

Investigators said the group was recorded on surveillance footage leaving a home on Louis Street just before 11 p.m. on June 24. They then walked toward an alley near Kaighn Avenue that Hill, 63, had entered minutes before, the affidavit said.

The suspects then walked with Hill as he exited the alley, and followed him back there when he returned a few minutes later. After a few minutes, Knight and a 15-year-old boy are seen leaving the alley.

Hours later, police were called to the site and found Hill’s body, the affidavit said. He had cuts on his forehead, as if he had been hit with a rock or something similar, a county medical examiner ruled. Hill also had a broken neck and jaw, and his cause of death was determined to be blunt-force trauma.

Police officers found bloodstained pieces of concrete around his body, which they believe were used in the attack.

Detectives later located a witness, who identified Knight from the surveillance footage, according to the affidavit. The witness said Knight had been planning the attack on Hill for days, and had seen video Knight said she recorded of the killing.

The witness told detectives she had asked Knight why she wanted to kill Hill, and the teen’s response was that “she did not care and does whatever she wants,” the affidavit said.

» READ MORE: Juveniles ages 12, 13, and 14 charged in beating death of homeless man in Camden. Five teens now face charges.

A relative of Knight’s later identified her from the same surveillance footage, and detectives obtained the teen’s phone through a search warrant. It contained the video of her taunting Hill as he lay unconscious in the alley, according to the affidavit.

Detectives later identified the 15-year-old seen leaving the alley with Knight and took him into custody June 30, police said. The three other suspects, a 12-year-old, 13-year-old, and 14-year-old, were arrested Nov. 24 and charged with homicide.

Their names, and the circumstances of their arrests, were not disclosed by police because they are juveniles.