Mourning relatives and friends of murdered Run-DMC star Jam Master Jay have told of their bewilderment at his death.

They said they cannot understand why a peace-loving family man with no known enemies was shot dead inside his New York studio.

Police are investigating whether the DJ - real name Jason Mizell - may have been killed in a personal feud, or as a result of ongoing rivalry between east and west-coast rappers.

But his teenage son, Jason Mizell Jr, said: "There's no reason. He didn't really do anything wrong."

Police are investigating the possibility of a feud involving Jam Master Jay

The co-founder of Run-DMC was shot once in the head at close range with a .40-calibre semi-automatic in the attack at 1930 on Wednesday (0030 GMT) on the second floor of his recording studio in Queens.

Two witnesses told investigators conflicting stories about the killing, which took place as Mizell, 37, played video games in a lounge with 25-year-old Uriel Rincon.

Theories

Rincon, who was shot in the leg, told investigators that a masked man opened fire after a struggle. Police recovered two shell casings from the shooting.

By Thursday night police had not established a motive or identified any suspects.

Mizell's murder has shocked relatives and friends

Colleagues questioned whether Mizell - known as a family man and social activist - would ever be caught in a violent flare-up.

Public Enemy frontman Chuck D, who credits Mizell with getting his group their record deal, said: "I'm very, very deeply saddened as well as angered over the loss of a man who was both a hero and a close friend of mine.

"We were allies and friends, travelled the world together, shared our thoughts and good times, and watched each other's children grow up."

Russell Simmons, founder of the Def Jam record label and older brother of Run-DMC rapper Joseph Simmons, said: "Before the media rushes to attribute this to east coast-west coast violence, they should examine Run-DMC's two decades of contributions and Jam Master Jay's personal character."

Success

Bereaved fans outside the crime scene laid flowers, candles, personal notes and an Adidas training shoe - a reference to the group's trademark footwear - with the words "RIP JMJ" written in marker pen.

Mizell, who was married with three children, joined colleagues Simmons (Run) and DMC (Darryl McDaniels) in 1983 to record the group's first single, It's Like That.

They went on to enjoy huge success during the 1980s, becoming the first rap act to have a top 10 hit in the US and the first to have a video screened on music channel MTV.