On Mutter Street, monuments to the murdered stand like altars.

Four memorials have sprouted from the pavement of this North Philadelphia street in the last three years, including one last week for Reyna Aguirre Alonso, 29, a deli clerk shot execution-style, possibly because she was a witness to an earlier killing on this drug-plagued street.

Around 7:40 p.m. Monday, a man in a ski mask entered the market and, without a word, shot Alonso four times. He took nothing.

Police have not named a suspect in her killing, but on Friday, the Philadelphia Police Fugitive Task Force and FBI arrested Jorge Aldea, 23, of North Philadelphia, in the November slaying of Louis Chevere.

Chevere, 22, was killed outside the store where Alonso worked, at Westmoreland and Mutter Streets. Detectives had interviewed Alonso, believing she may have seen the killing from a window of her apartment above the store. It's not clear whether she helped investigators, but her family said she feared being targeted for having talked with police at all.

Police issued a warrant for Aldea earlier this month. On Monday, the Philadelphia Daily News published his photo in its "Most Wanted" section. Alonso was gunned down that night.

Authorities tracked Aldea to an apartment in the Bronx. He awaits extradition to Philadelphia, where investigators will interview him in Alonso's killing.

Aldea, known as "J Rock" in the neighborhood, has avoided prison despite 12 arrests on assault, weapons, and drug charges.

When he was 16, Aldea was arrested in the shooting of a man in the neck. At 17, he allegedly fired a gun outside a bar in midafternoon; bullet fragments struck a year-old child in the neck and face. The child was eating at a restaurant with his mother.

One case was withdrawn, the other dismissed.

In February 2011, Aldea was charged with firing a 9mm handgun at a woman in a car. That case was withdrawn after a witness failed to show up.

Starting at age 15, Aldea was arrested four times on charges of selling drugs; he received only six months of probation for a 2009 conviction.

Around Mutter Street, he was feared as a dangerous man.

"Long as I've known him, he just thought he was invincible," said a 22-year-old man on Mutter who said he grew up with Aldea. "He's always been fascinated with guns. He's always had an arsenal and would walk up and down like he was king . . . and trying to put fear in everybody's heart."

According to police reports, Aldea had sold drugs on Mascher Street, one block over from Mutter, and had shot Chevere - who had recently gotten off house arrest on drug charges - over a dispute.

Chevere, who was known around Mutter as Omer, had written his name on the street signs. On one stop sign, he wrote, "Can't STOP Omer." Aldea allegedly killed him just feet from the sign around midnight Nov. 25.

Three nights later, someone shot up a sidewalk memorial to Chevere.

Aldea was arrested on Dec. 21 after patrol officers spotted him carrying a loaded handgun into a North Philadelphia grocery store. Nine days after his arrest, a ballistics test matched his gun to the casings at the Chevere memorial.

Once again, jail couldn't hold him.

On Jan. 5, over an objection from the District Attorney's Office, Common Pleas Court Judge Nazario Jimenez Jr. reduced Aldea's bail from $50,000 to $20,000. Before dawn on Jan. 11, Aldea posted 10 percent and was free.

Later that day, a warrant was issued for him in Chevere's killing.

On Mutter Street Saturday morning, children sat on steps, playing "I Spy." None paid attention to the reminders of violence lining the street.

In a vacant lot, religious statues and Corona bottles adorn the weatherworn shrine to 18-year-old "Macho," shot dead in 2009.

On the porch of an abandoned, bullet-pocked house, a rain-soaked Bible, a pair of white Adidas shoes, and a Hennessy bottle commemorate Chevere's life.

The sidewalk memorial to Samantha Houston, 19, shot dead by an invader in the bedroom of her Mutter Street home in 2008, is gone now, erased by time and more tragedy.

Nor is there a marker outside the rowhouse where Antonio Rodriguez, known as the Kensington strangler, was caught a year ago.

At Alonso's tent-covered memorial outside the Caribe Mini Market, where she had worked for two years before her death, there were no liquor bottles or stamped-out blunts - just flowers and candles and Magic Marker remembrances of a pretty woman who sent money home each week to her ailing mother in Mexico.

Contact staff writer Mike Newall at 215-854-2759, mnewall@ phillynews.com, or @MikeNewall on Twitter.