By Joe Holden

PHILADELPHIA (CBS) — Philadelphia marked a record 562 homicides in 2021. One of them continues to haunt police — Lucas Booker was ambushed and killed inside his home. More than a year later, detectives are trying to figure out why.

Sunday, Jan. 31, 2021, Booker had just gotten home. It was moments before 3 in the morning.

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“After a night of spending time with family and friends, Mr. Lucas Booker returned to a residence,” Lt. Hamilton Marshman said.

Booker, a 20-year-old, walks into his home in the 4900 block of Rorer Street in Feltonville, where homicide detectives say he was ambushed.

“Upon entering, he was approached by a male who produced a handgun and shot Mr. Booker multiple times,” Marshman said.

Marshman said it “absolutely” was an assassination and Booker didn’t see it coming at all.

Booker was rushed to Einstein Medical Center, where he died from multiple gunshot wounds.

Police don’t know why Booker was targeted.

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The murder closed out the first month of 2021 — Philadelphia’s deadliest year on record.

Philadelphia police homicide detectives have hit some snags in their pursuit of who did this. They do have surveillance video. They’ll acknowledge it’s not the best of quality, however, they believe someone will notice something in helping them track down the killer.

“The video, even though it’s not the best quality, however, you see the offender outside of the location,” Marshman said. “Appears to be standing around waiting for Mr. Booker return home and then you see the offender flee the location after the murder takes place.”

Distraught family members have held onto hope that someday there will be justice for Booker.

“Mom lost her son,” Marshman said. “We stay in contact with her. We have reached out to her and let her know different things that we are doing as far as the investigation. She is a grieving mom. She wants to know why this happen and she wants to know who did it.”

If you have any information, you’re asked to call 215-686-tips.

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For a list of gun violence resources in Philadelphia, click here.