UPDATED 10/10/11 10:47 a.m.

CHICAGO (CBS) — A Logan Square neighborhood man goes to court Monday, on charges that he murdered one of his sisters and tried to kill another over the weekend.

As WBBM Newsradio’s Regine Schlesinger reports, Francisco Martinez, 28, of the 2300 block of North Harding Avenue, is charged with one count of first-degree murder and one count of attempted murder.

The charges were approved Sunday afternoon.

LISTEN: WBBM Newsradio’s Regine Schlesinger reports

Early Saturday morning, Martinez was drinking and partying with friends in his backyard when his sister Isabella, 22, came out and told him to keep it down. When he ignored her, she got their 35-year-old sister, Erminia to intervene, <a href="” target=”_blank”>the Chicago Tribune reported.

Police say an argument erupted, and Francisco ended up shooting both of his sisters.

Isabella was pronounced dead at Advocate Illinois Masonic Medical Center at 9:15 a.m. Sunday, according to the Cook County Medical Examiner’s Office.

An autopsy Sunday determined Martinez died of a gunshot wound to the head and her death was ruled a homicide, according to the medical examiner’s office.

Erminia was taken to Advocate Illinois Masonic Medical Center, where she was reported in stable condition, police said.

Their mother, Carmella Martinez, told the Tribune Francisco loved his sisters and would have done anything to defend them if someone else had threatened them, but he went off the deep end after drinking.

Meanwhile, a longtime community activist sees the shooting as endemic of the scourge of street gangs and their influence in the area. Larry Ligas, Chairman of Logan Square Concerned Citizens, said he believes the gunman is a member of a local street gang that police have been working to eradicate.

The block the shooting took place on and in particular the building where it occurred was a location that has “kept coming up” in meetings with other community residents, police and elected officials about neighborhood violence, he said.

“The gangs are getting mean, and organized to protect what little turf they have left,” Ligas said. “Even if it means shooting their own family members. They aren’t above shooting their own family members. Their gang comes first — before their own family.”

He said the gang members have “put such a fear” into their neighbors that people are hesitant to call police when there is trouble. While the neighborhood’s quality of life has been improving, “we could do a much better job if the aldermen stepped up.” Ligas said. He said he’s tried to convene the area’s three aldermen to come up with strategies to address the gang violence, with limited success. He commended some efforts made by Ald. Ariel Reboyras (30th) and Rey Colon (35th), but he remarked, “I’m tired of all the finger-pointing. We need to work together.”

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