Lisa Underwood, 34, and her son, Jayden, 7, have been missing since Saturday when they were no shows at her baby shower. Family members who went to her home found it empty, with blood on the floor and no sign of forced entry.
Fort Worth police Lt. Gene Jones said Monday's discovery of the SUV - which had been described in a nationwide Amber Alert - is a major step forward in the investigation. He said, though, that authorities have little information to share.
Police declined to say whether there are any signs of a struggle in the vehicle.
Late Monday, investigators removed a roll of carpet from the red brick home, which remains surrounded by police tape.
"There are a lot of questions we have," Jones said. "We haven't answered all those questions and that's why we're being very careful about what we tell the public."
The blue Dodge Durango was found alongside Interstate 35, the major thoroughfare leading north to the Oklahoma state line. Police declined to say what, if any, evidence was found inside. The keys to the vehicle were found nearby.
Officers on horseback rode up and down surrounding farmland for hours after the SUV's recovery Monday morning, but ended the day without finding of Underwood or her son, a first-grader described as the light of his mother's life.
"They are each other's lives," Marla Hess, Underwood's aunt, told the Fort Worth Star-Telegram for Tuesday editions. "They created a world that no one else can penetrate. We are going to find them together - regardless."
Underwood is not married, Jones said. He said her son's father and the father of the baby were among those being contacted by police, but he added that investigators have not narrowed the investigation to any particular suspect. Both men were described as cooperative.
Underwood is a co-owner of Boopa's Bagel Deli with Holly Pils, who said she last spoke with Underwood on Friday night. Underwood is seven months pregnant.
Pils said Underwood named the bagel shop after a nickname that her mother had given her grandson.
"He wanted to be referred to as one of the owners because he said, `My name is on the building,"' Pils said.
Cards from well-wishers have piled up at the bagel shop. Several notes were taped to the inside window and a large brown teddy bear was placed on a table by the window. One of the notes said, "God Bless Lisa and her two little angels."
Outside the family home, someone wrote a chalk message on the concrete, wishing them a quick return. Friends planned a candlelight vigil for Tuesday night.
By Matt Curry