The bullets recovered from both victims are consistent with those found in the handgun that was located near the two, one of two unregistered pistols found in a search of the home Monday night.
"Little was gleaned from the autopsy," said Pleasanton police Lt. Jeff Bretzing.
Lab results are needed to confirm whether the handgun found nearest the victims was actually involved. Police said those results and other key evidence may not be available until some time next week.
"Until that time, we are unable to determine the exact nature of the shootings and investigators will continue to follow up on all leads," a news release said. "Christopher Burton, the husband of Amy Freeman Burton and stepfather of Ainsley Freeman, remains cooperative in this investigation."
Christopher Burton told investigators they obtained the guns from his brother in Arizona.
A news release on Tuesday said Burton told police his wife had recently become paranoid as a result of an incident regarding Ainsley. He said he and his wife reported to the Pleasanton Police and the FBI in February of this year that Ainsley was in communication via text messages with a suspicious male located in the state of Kentucky.
However, an investigation launched by the Pleasanton Police Department and the FBI revealed the individual was a 16-year-old male and that the activity did not constitute a criminal violation.
"We have no reason to believe at this time there is any connection between this earlier report and the shooting deaths," Bretzing said.
Police received a call to the home at around 6 p.m., Bretzing said in his initial briefing on the double slaying Monday night.
"Officers, upon arriving, encountered 37-year-old Amy Freeman Burton who had a fatal gunshot wound," Bretzing said. "They also encountered her 13-year-old daughter, Ainsly Freeman who had also been shot. Ainsly was taken to Eden Trauma Center in Castro Valley, where she succumbed to her injuries."
A warrant was written so police could search the house and as of midnight Monday, the search had just begun. An Alameda County Sheriff was on scene and technicians were going through the home.
The 13-year-old was a student at Hart Middle School.
"Our hearts go out to the friends and family. Please take this time to recognize those around you and take care of each other," Hart Middle School Principal Terry Conde wrote in a statement. "Using the example set by our students, it is important that we continue to come together as a Hart community."
Conde estimated that 50 students at Hart asked for counseling on Tuesday. Freeman was said to have been an excellent student at both that school and schools she attended in Missouri, where the family lived before relocating here.
Amy Freeman Burton's mother, Linda Walp of Chesterfield, Mo., said her daughter and granddaughter had moved to Pleasanton late last year after Christopher Burton found a job.
Cyndy Bormann, a counseling secretary at Hart, said that all student counselors in the Pleasanton Unified School District were at the school Tuesday and will likely be there through the week as needed.
"We are focusing on taking care of our students, she said. "We will be providing grief counseling to all students. We have additional counselors on site."
Pleasanton Middle School Principal John Whitney said that his three counselors have been dispatched to Hart Middle School to assist with grief counseling on site.
Whitney said the third school in the district, Harvest Park Middle School, has also dispatched several counselors and that Hart has three counselors on staff.
"Our counselors have all been dispatched to assist with the students and staff to help them get through this," Whitney said.
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