Updated

Two of three babies found dumped along the Mississippi River in recent years probably came from the same mother, authorities revealed Tuesday in the hopes of jump-starting their investigation.

They believed the children, a boy and a girl, had separate fathers, they said.

"I guess what we have with these first two children is cold-blooded murder," Goodhue County Sheriff Dean Albers said. "If it was one child you might see it as the act of a desperate mother, but what I think what we have here is premeditated murder."

Tests done by the state Bureau of Criminal Apprehension found that the first two babies, found in 1999 and 2003, were probably related. The third child, a girl whose body was found in March, is not related to the first two.

DNA tests done by a Florida lab and paid for by Goodhue County indicated the two related babies were probably Caucasian. The third was believed to be of American Indian descent.

Investigators believe all three infants were born alive. Autopsies did not reveal the cause of death.

After the discovery of the first two infants, a local couple paid to have them buried next to their stillborn daughter under headstones that read "God's Little Angel."

Dozens of women have been tested and eliminated as possible mothers, Albans said.

"These deaths are tragic," he said. "Shortly after these children were born, they were thrown away — thrown away to die cold and alone."