The father of two children whose remains were found in a shallow grave more three years after they disappeared was charged Tuesday in their deaths.

Dan Porter, 44, — who already is serving a 38-year prison term for kidnapping his son Sam, 7, and daughter Lindsey, 8, to terrorize their mother — was charged with two counts of first-degree murder in their shootings.

The children's bones were found in September in a wooded area near the Missouri River in nearby Sugar Creek and were identified using dental records. The children had been missing since Porter picked them up at their mother's house for a weekend visit in the summer of 2004.

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According to the probable cause statement filed with the charges, Porter told investigators that he had planned to kill his children for two days before he picked them up from his estranged wife; the couple have since divorced.

Jackson County prosecutor Jim Kanatzar said the children were killed with a handgun, but he did not provide additional details. He said he would decide within the next month whether to seek the death penalty.

"There is absolutely no explanation for actions like this," he said.

Porter was to be arraigned Tuesday in Jackson County Circuit Court in Independence. The prosecutor's office was not sure if he had an attorney yet, and the public defender who represented him in the kidnapping case did not immediately return a call Tuesday.

After his arrest on the kidnapping charges, Porter told authorities several stories about what he had done with his children, including that he had cut them up and that he had strangled them. On Sept. 7, he told prison officials and the FBI where to find the bodies, according to the probable cause statement.

The area where the children's remains were found is where Dan and Tina Porter met to swap the children. Police said Dan Porter had asked her to meet him near the area so they could exchange vehicles.

Tina Porter, 44, of Independence, has said he tried to get her to drive her pickup into the woods by telling her that he had stashed $50,000 there and wanted to get it. She refused.