The vehicle matches the description of Kempe's white 2020 Acura MDX with license plate NPM-2597, authorities said Monday.
According to Fort Bend County deputies, information suggests the body found in the vehicle is that of Kempe. Absolute identification and a cause of death are pending autopsy, deputies said.
The Richmond mother had been missing since last Friday.
Deputies said the car became visible as water levels in Jones Creek receded following heavy rains last week. Her car was found submerged in the creek about 1,000 feet north of FM 359.
"The investigation of this tragic incident is ongoing by our team," said Sheriff Eric Fagan. "I request that your thoughts, prayers and respect for privacy be extended to Allison's family during this difficult time."
Kempe left a restaurant in the 6300 block of FM 1463 around 10:30 p.m. Friday. Investigators said she was believed to be headed home in the Richmond area of FM 359 and FM 723, but never showed up.
Family and close friends gathered along FM 359 near the Jones Creek on Saturday as Texas EquuSearch searched for the missing mother of two and her missing vehicle in the water.
"We got one fact. She's missing and been missing too long," Miller said Sunday. "Part of the investigation is that her phone last pinged pretty close to this area, and she actually said she was in some water, and her car was taking on water."
Kempe is the mother of two young boys, ages 5 and 7.
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