A videotape, shot near Phoenix, seems to show some large piece departing the shuttle as it hurtled through the sky at more than 18 times the speed of sound.
At about the same time, Cal Tech astronomer Anthony Beasley also saw something fly off the spacecraft.
"At one point there was a particularly bright light as things were beginning to separate from the shuttle and fall back and join the trail," said Beasley.
With new evidence that Columbia started breaking up earlier than NASA thought, the hunt for remains and shuttle debris has been stepped up all the way west to California. But one of the most intensive search areas is about 140 miles northeast of Houston, in and around Hemphill, Texas.
CBS News Correspondent Robert Berger reports NASA has informed Israel that the remains of Israeli astronaut Ilan Ramon have been found and identified. The army says the remains will be brought to Israel in the coming days, and the funeral will be held next week. Israeli officials say the finding of the remains is a relief to the family, because under Jewish Law, a funeral cannot be held unless the body is found.
Recovery teams in Arizona have found what they believe to be pieces of the shuttle; that and the new pictures bolster data monitored during the final minutes of flight that revealed a cascading series of failures as Columbia raced for home.
Sensors in the left wheel well showed a spike in temperatures, as did a sensor on the fuselage above the left wing. Perhaps more importantly, the shuttle started pulling to the left, ultimately to the point where its flight control computers could no longer compensate.
NASA engineers don't yet understand what caused this unusual "drag" on the left side. But it's possible that damage to the insulating tiles that protect the shuttle on its fiery reentry could have significantly disrupted the airflow under the left wing; that could have created such an extreme "yaw" or skid to the left that the spacecraft was ultimately ripped apart.
"The shuttle started turning, started being dragged to the left," said Edward Crawley of MIT. "It was that turning that caused the heating on the shuttle and the aerodynamic loads to change enough to cause the vehicle to fail."
NASA engineers still don't know if this incident during launch may have set up a fatal series of failures. A piece of insulation from the external fuel tank hit the underside of the left wing. NASA suspects that may have caused some "localized damage" to the heat tiles, but shouldn't have put the spacecraft and its astronauts in danger.
Still, there have been similar incidents before that did not lead to tragedy. Last June, insulation was shed from the fuel tank during the launch of Endeavour.
And five years ago, more than 300 of Columbia's tiles were peppered with damage by bits of insulation.
A NASA report written after that 1997 incident concluded "the extent of damage at the conclusion of this mission was not normal."
Texas National Guard troops were called out Tuesday to join the search for human remains and shuttle debris. CBS News Correspondent Bill Whitaker reports hundreds of Guard troops joined workers on horseback and volunteers on foot searching more territory, finding more remains.
"We found more cabin components including one of the seats from the cockpit," said Nacogdoces County Sheriff Thomas Kerss. "We found more of the remains from some of the individuals involved."
The largest find so far, shown on CBS News Monday night, was Columbia's nose cone. It landed across the street from Nathan Ener's house.
"It went into the ground at an angle and it pushed all the ground up about three-foot high on the back side of it. It had tree roots sticking up in the air," said Ener.
When the fire rained down, East Texas was ground zero.
Retired Adm. Harold Gehman, the head of the panel investigating the disaster, called it hallowed ground. He came to see firsthand.
"We'll be reconstructing the flight of every piece that came to earth," Gehman said.
And, they hope, even those that landed in water. Investigators took a fisherman out on nearby Toledo Bend Reservoir, where he reportedly saw a huge chunk of the shuttle splash down. They are using sonar and have called in divers.
"We have no visibility. It's cold. Underwater recovery either by hand or using equipment is always difficult," said diver Don Martin.
It's a daunting task, but searchers seem undaunted. Adm. Gehman said don't expect quick solutions, but people here say they won't rest in peace until the job is down.