TAMPA, Florida — The wife of a military officer shot and killed her son on the way to soccer practice, then drove to their upscale home and shot her daughter in the head while she studied at her computer, police said Friday. Afterward, the woman told detectives she killed the teens for being "mouthy."

Julie Powers Schenecker admitted the slayings after officers found her covered in blood on the back porch of her home Friday morning, police spokeswoman Laura McElroy said. Schenecker's mother had called police from Texas because she was unable to reach the 50-year-old woman, who she said was depressed and had been complaining about her children.

Schenecker's husband, Parker Schenecker, is an Army colonel stationed at the headquarters of U.S. Central Command at MacDill Air Force Base in Tampa. The father had been away for several days when the killings happened, said CentCom spokesman Lt. Col. Michael Lawhorn, describing him as a career Army intelligence officer.

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Police said Parker Schenecker was in Qatar and was told of his children's deaths on Friday.

Julie Schenecker left a note detailing her plans to kill her disrespectful children and then herself, saying "they talked back and were mouthy and that she was going to take care of it," McElroy said. She provided the same motive to police who interviewed her.

"I think we will never understand how or why a mother could take the lives of her children," McElroy said. "That was the only reason she provided to our detectives."

The body of Schenecker's daughter, Calyx Powers Schenecker, 16, was found in an upstairs bedroom, McElroy said. The body of her son, Powers Beau Schenecker, 13, was found in an SUV in the garage.

An arrest affidavit said Schenecker shot her son twice in the head "for talking back" as she drove him to soccer practice Thursday night. She drove home, went inside and shot her daughter in the back of head while the teen sat at a computer doing homework, then shot her in the face, the affidavit said.

McElroy said investigators believe the teens "never saw it coming." Both were killed with a .38-caliber pistol.

Julie Schenecker was jailed and charged with two counts of first-degree murder. Wearing a white jumpsuit, she was led into a county jail later Friday visibly shaking and being supported by a sheriff's deputy.

The family's home is on a cul-de-sac in a gated country club community in north Tampa. Hillsborough County property records show that the Scheneckers bought the house in 2008 for $448,000. It now has a market value of $261,000.

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Charanun Soodjinda, 38, lives across the street. He said the Scheneckers moved in about two years ago and "fit right in." The couple's two children often played in the cul-de-sac with other neighborhood kids, and Julie Schenecker seemed to be at home a lot.

"They seemed like a nice family," Soodjinda said. "I never thought this would happen. How could you do that to your children?"

Seena Jain, who carpooled with the Schenecker children and her own daughter, Sheema, 15, told the St. Petersburg Times that recently Parker Schenecker had picked up his wife's carpooling shift while she recovered from a serious car crash that happened about a month ago. Details of the accident weren't immediately available.

Julie Schenecker's Facebook page says she earned a bachelor's degree in physical education from the University of Northern Iowa.

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Many of her Facebook comments seemed to suggest how proud she was of her children. In one photograph posted by her husband, daughter Calyx Schenecker is seen posing with six other girls from a cross country team.

"that's my baby! doin' something I could never do-3.2 miles!!" she wrote.

In another post, she responded to a friend whose status said, 'Its Mommy Week! Post the day you became a Mommy"

Schenecker wrote: "calyx powers 9/12/94 in germany and powers beau 9/29/97 in honolulu!"

In a post from September, she responded to another friend's status, which cited a quote from Henry Ward Beechner, "Hold yourself to a higher standard than anybody else expects of you."

"I needed that advice today-have a 16 yr old daughter!"

Sylvia Carroll, who attended Muscatine High School in Iowa with Julie Schenecker, said she was a popular and athletic girl who starred in basketball in the late 1970s. They reconnected about a year ago on Facebook.

"I'm just in shock," said Carroll, who now lives in Austin, Texas. "I can't believe this."