Casey Anthony
© Joe Burbank/Orlando Sentinel/MCT/GettyCasey Anthony
The search was made from a computer in Anthony's home on the day her daughter was last seen alive.

Florida sheriff's investigators missed a key piece of evidence - a Google search of "fool-proof" suffocation - in the Casey Anthony murder probe, they acknowledged Sunday.

The search, made from a computer in Anthony's home on the day her daughter was last seen alive, could have helped convict her in the death of 2-year-old Caylee, said Orange County Sheriff's Capt. Angelo Nieves.

"It's just a shame we didn't have it," prosecutor Jeff Ashton told an Orlando TV station.

In July 2011, a jury acquitted Anthony, 24, of murdering Caylee, whose skeletal remains were found six months after she vanished in a wooded area near her home.

Nieves said the sheriff's office's computer investigator missed a June 16, 2008, search made from a computer Anthony used.

The investigator pulled 17 vague entries from the computer's Internet Explorer browser, but did not analyze the Mozilla Firefox browser, where the potentially incriminating evidence was found, Orlando news station WKMG reported.

Nieves said detectives have not determined if Anthony made the search for "fool-proof suffication," misspelling "suffocation." She shared the computer with her father, George Anthony.

Unaware of the online search, prosecutors argued during the trial that Caylee was poisoned with chloroform and then suffocated by duct tape placed over her mouth and nose.

A computer expert for Anthony's defense team initially found the search prior to the trial.

Anthony's defense attorney, Jose Baez, first mentioned the search in his book about the case but suggested George Anthony was behind it.

Baez said George Anthony wanted to kill himself because he was guilty over Caylee's accidental drowning in his backyard pool.