Maybe nobody wants to testify against Quasheam Richburg.

The 20-year-old North Philadelphia man, whom police identified Friday as the suspected shooter in Thursday's slaying of convenience-store clerk Mustafa Shaker, has been arrested three times since last year. Richburg has been charged with an array of crimes that include making terroristic threats, illegal gun possession and false imprisonment.

In two cases, the charges were withdrawn and court records state that witnesses couldn't go to court because of school or because they just "failed to appear."

Heck, Richburg didn't even bother to show up for a May 10 court appearance in the third case, prompting Common Pleas Court Judge Rayford Means to issue a bench warrant for his arrest the same day.

But at least one person must have grown a pair since Thursday to tip off homicide detectives about Richburg's alleged involvement in the North Philadelphia shooting. Hours after the shooting, cops released surveillance images of the crime, hoping it would lead to such tips.

Police on Friday issued a murder arrest warrant for Richburg, who lives on Ridge Drive near 27th Street, North Philadelphia, according to court records. Richburg is known to frequent the Johnson Homes and "is considered armed and extremely dangerous," said Homicide Unit Capt. James Clark.

He said that Richburg's identity came from a couple of tips and "some real good detective work."

Now, Clark is asking for the public's help in locating the suspect. The owner of Trax Food Store, where Shaker worked and was killed, has offered a $1,000 reward for information leading to the capture of suspects in the murder.

The fatal attack began before 3 a.m. Thursday when two men, one carrying a sawed-off shotgun, entered Trax Foods. The men demanded money from Shaker, 50, but he refused. Richburg allegedly fired two shots, hitting Shaker once in the head and killing him instantly, Clark said.

The Egyptian immigrant is survived by a wife and two children.

The killers didn't get a dime from the store, police said. In fact, the video seems to show that they left money on the counter.