A Cheyenne heart transplant recipient and her mother-in-law were killed Saturday in a plane crash outside Rock Springs, authorities said.

Sweetwater County Coroner Michael S. Vase said Judith Tottenhoff, 49, and her mother-in-law, Madelyn Tottenhoff, 69, also of Cheyenne, were killed in the 11:53 a.m. crash.Judith's husband, Donald Tottenhoff, 51, was injured in the crash and was flown to Salt Lake City, where he was listed in critical and stable condition at LDS Hospital Saturday evening.

The crash occurred about 1.5 miles from the approach end of a runway at the Rock Springs City-County Airport, Vase said.

The single-engine Piper Cherokee had taken off from the airport about 10 minutes earlier and was apparently trying to go back when it crashed. Vase said the reason for their return is unknown.

Investigations are being conducted by the coroner's office, the sheriff's department and the National Transportation and Safety Board.

The plane had originated in Salt Lake City and had stopped in Rock Springs to refuel before continuing on its way to Cheyenne, Vase said.

Judith Tottenhoff was in Salt Lake City for a medical checkup. She celebrated one year with her new heart on May 25.