LaCross said it appears that Williams may have fallen and then as Haley went to call for help, she fell as well.
Overnight temperatures in the area dropped to as low as 11 degrees, with wind chills as low as minus 8.
Martha Williams and Jean Haley, both 97, were found by a neighbor Saturday morning.
They were both found outside Jean's home, with Martha face down near her auto in the driveway and Jean's body in the garage.
NBC2 News reported that the two women had gone out to dinner with a younger sister, 89, on Friday night.
Police said they don't believe any foul play was involved.
Investigators believe that Williams, of East Providence, R.I., may have fallen in the driveway walking to her vehicle, according to a police statement. Haley's body was found in the garage. Their causes of death are unclear, although police said "extreme cold temperatures" on the night they fell may have been contributing factors. They were rushed to Rhode Island Hospital in Providence in critical condition, but died shortly after.
"They came into life together and they died together", John Haley, one of Jean Haley's sons, told TIME on Monday. He was an Army captain in World World II and was described by the Journal as "instrumental in liberating concentration camps in Belgium".
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