Last week, Daniel Duignam was a Temple University junior just days away from finishing his final exams and heading into summer.

But Saturday night, according to police, he called 911 from his apartment near the school, saying he couldn't breathe. Police believe he had already been shot multiple times. By the time first responders arrived, he was dead.

Who shot Duignam and why remained a mystery Monday. Homicide Capt. John Ryan said investigators believe Duignam knew his attacker because there were no signs of forced entry, but did not elaborate.

Ryan said the inside of the residence on the 1700 block of West Diamond Street appeared ransacked, and investigators believe cash was taken. He declined to say if police found drugs, alcohol, or anything else of interest inside.

Duignam, 21, was a student at the Fox School of Business, a native of Northampton County, Pa., whose grandfather was once the mayor of his hometown, Tatamy. According to his LinkedIn profile, Duignam was a risk management and insurance student.

Temple's president, Richard M. Englert, said in a statement Sunday that Temple would "enhance patrols in the areas surrounding campus as the investigation moves forward." He and others on social media lamented Duignam's passing; the Temple student government, in a statement, encouraged students to speak with on-campus counselors.

A Temple spokesman said Duignam was the sixth Temple student to die since August.

Jenna Burleigh, 22, was murdered at the beginning of the school year. Joshua Hupperterz, 29, has been accused of killing her at his North Philadelphia home and taking her body in a storage bin to his grandmother's house in the Poconos.

In October, Richard Dalcourt, a 19-year-old freshman, fell to his death from the sixth-floor window of a dorm building, which authorities later deemed a suicide.

That same month, Cariann Hithon, 22, was shot dead by police in Miami after police said she crashed into a detective's cruiser.

And two students died of fatal drug overdoses in the weeks after Thanksgiving.

Duignam's death was one of at least three homicides in Philadelphia this weekend, according to police. At least 13 people were shot and five were stabbed in incidents between Friday night and Sunday, police said.