Police had been called to Gilbert shooting home before

GILBERT, AZ (CBS5/AP) -

Police in Gilbert said a woman who was shot and killed by her boyfriend with neo-Nazi ties called authorities earlier this year to report that he had choked her.

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• READ: CBS 5 Exclusive Coverage of Shooting
• READ: Domestic violence at root of shootings, police say (5/3/2012)
• READ: JT Ready had history with white supremacy movement (5/2/2012)
• READ: Russell Pearce reacts (5/2/2012)
• READ: Neo-Nazi and infant among Gilbert shooting victims (5/2/2012)
• SLIDESHOW:
Police investigate Gilbert shooting (5/2/2012)

• SLIDESHOW: J.T. Ready

• SLIDESHOW: Victims

CBS 5 News learned that since November 2009, police have been called to the house five times prior to the shootings. Only one was domestic violence related. That call came in February 2012 to report a domestic violence incident that reportedly took place five to six months prior.

Mederos reported that Jason Todd Ready had choked her, but Gilbert police Sgt. Bill Balafas said there was not enough evidence to make an arrest and no charges were filed.

It isn't clear why Mederos decided to report the incident so long after it happened.

In other developments on Thursday, half a dozen grenades were among the military munitions found in the home.

U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives Special Agent Tom Mangan said Thursday the agency is tracing the serial numbers of six 40 mm projectile grenades discovered in Ready's house.

Mangan said the explosives are strictly military-issue, should not be in a residence and that they are illegal for civilians to possess.  

Luke Air Force Base has since taken the grenades and destroyed them.

Gilbert police said the four others killed in Wednesday's shootings include 16-month-old Lily Lynn Mederos, 23-year-old Amber Nieve Mederos, 38-year-old Lisa Lynn Mederos and 24-year-old Jim Franklin Hiott.

Police said a woman heard arguing before the shooting spree, leading police to believe that domestic violence was at the root of what they were calling a horrific murder-suicide.

Balafas said the 19-year-old daughter of one of the victims, Lisa Mederos, was in the home and also heard gunshots.

Balafas said the woman did not see the shootings, but found the bodies and was one of the people who called 911.

Two separate 911 calls made after shootings

Police also said on Thursday that they have listened to the 911 tapes and determined two separate 911 calls came from 530 W. Tumbleweed. They said they believe the first caller was Lisa Mederos. She requested police response to the home for a "domestic violence" fight. Gunshots were heard on the call seconds prior to the line disconnecting.

A second 911 call came from a woman inside the home who, after hearing the shots, exited a room within the home to find three gunshot victims.

Investigators said they will await scientific and medical analysis of the victims before signing off on a motive. The results are anticipated to take several weeks.

Copyright 2012 CBS 5 (Meredith Corporation).  All rights reserved.  The Associated Press contributed to this report.