Julie Powers Schenecker Update: Fla. Mom Indicted for Murder in Her Teens' Slayings

(CBS/AP) Julie Powers Schenecker, the Florida mother accused of fatally shooting her two teenage children for excessively "talking back," was indicted on two felony charges of premeditated first-degree murder Thursday.

PICTURES: Julie Powers Schenecker Kids

Authorities say the 50-year-old Tampa mother bought a .38-caliber revolver the weekend before the Jan. 27 shootings and apparently wrote a note prior to the shootings in which she referred to her plan as a "massacre."

According to an arrest affidavit, Schenecker shot her 13-year-old son Beau in the head twice "for talking back" while they were in the family car on their way to his soccer practice. Schenecker then returned to their upscale home and shot 16-year-old Calyx in the face while the girl studied at her computer, states the report.

Tampa police spokeswoman Laura McElroy told the St. Petersburg Times the mother also observed that the three-day waiting period to take a gun home would "delay the massacre."

Army Col. Parker Schenecker, the children's father, was in Qatar when he learned that Caylx and Beau had been found dead in their Tampa, Fla. home and that his wife was accused in the teenagers' slayings.

At a memorial service in his hometown of Fort Worth, Texas, Parker Schenecker said his children lived their lives with purpose by helping others.

"I know my children were loved," he told more than 500 mourners Tuesday. "Now we all must go forward to honor them with love and respect for each other."

Julie Powers Schenecker is scheduled to be arraigned Feb. 16.

COMPLETE COVERAGE OF JULIE POWERS SCHENECKER ON CRIMESIDER