The grieving sister of homicide victim Anthony Spencer stood in front of a mass of cameras and reporters on Tuesday, issuing a powerful command for witnesses to step forward.

Susan Spencer stood before a microphone, shaking slightly as her parents gathered nearby, and told her brother's friends that their family was disappointed in their silence and lack of "loyalty".

Anthony Spencer, 23, died Saturday after being shot inside a Scarborough recording studio.

Police said that friends drove him to hospital before abandoning him, and have not been helpful in the investigation.

"I'm from the old school. My friends would have never done that to me. My friends would have come forward. You invite people into your life to share parts of your life, to share memories. You are supposed to have each other's back," Susan Spencer said on Tuesday.

"He invited you into his life to be his friend. Please show your loyalty in coming forward and bringing forth the person who is responsible for taking my brother's life."

According to police, Spencer and a group of friends were recording hip hop music in a studio at 799 Brimley Rd., near Lawrence Avenue East, shortly before 4 a.m. when they were confronted by a group of people armed with at least one gun.

Spencer was shot several times at close range and the suspects fled the scene. Spencer's friends rushed him to hospital, dropping him off before fleeing in two cars. The friends have been contacted by police, but have not been helpful in the investigation.

On Tuesday, homicide investigators took the unique step of issuing a pointed request for assistance, asking the group of friends to end their silence and help bring Spencer's killers to justice.

"This witness appeal is not being made directly to the general public, it is being made directly to the friends and associates of Anthony Spencer," Det. Sgt. Gary Giroux told the press conference.

"I am asking the friends of Anthony Spencer now to tangibly demonstrate their affection and loyalty to him by coming forward and telling police what they saw that night."

Giroux said witness participation is the single-biggest challenge faced by the homicide squad.

"I understand that witnessing a homicide must be a frightening event and certainly witnessing the homicide of a close friend must be absolutely devastating," he said, adding that dangerous people were in the community.

Victim was aspiring rapper

Spencer, the father of a three-year-old daughter, was an aspiring rapper who performed under the name Tony Trapz.

Giroux told CTV Toronto's Tamara Cherry on Tuesday that police were considering whether Spencer's lyrics may upset someone and led to the shooting.

With files from CTV Toronto's Tamara Cherry