10/10/2011 12:03 pm ET Updated Dec 10, 2011

Francisco Martinez Charged With Fatally Shooting His Sister, Wounding Another

A Chicago man was charged Sunday with shooting two of his sisters, killing one of them and seriously injuring the other during a dispute behind their Northwest Side home.

Francisco Martinez, 28, allegedly murdered his sister Isabella, 22, and attempted to murder his older sibling, Erminia, 35. The Chicago Sun-Times reports that he allegedly shot his sisters about 4:40 a.m. Saturday in the midst of a party in the backyard of the Logan Square home where they lived.

According to the Chicago Tribune, the dispute began when Isabella came home around 2 a.m. Saturday to her brother and his friends partying in their back yard on the 2300 block of North Harding. She and her sister Erminia reportedly asked her brother to stop the party sometime around 4 a.m. and an argument ensued.

The mother of of the accused shooter and his sisters, Carmella, told the Sun-Times that her son "loved them … but he needs a lot of time to think because what he did was terrible." She said alcohol was a factor in what became a fatal altercation for her daughter.

"He had been drinking all afternoon and part of the night," Carmella said. "The girls wanted his friends out of the yard and they were insulting and criticizing him. He was too drunk to see their point of view.”

Erminia, who was taken to the Illinois Masonic Medical Center in serious condition, is expected to be released from the hospital this week.