Key Casey Anthony evidence missed CASEY ANTHONY CASE

In this Sunday, July 17, 2011 file photo, Casey Anthony, front right, walks out of the Orange County Jail with her attorney Jose Baez, left, during her release in Orlando, Fla., after being acquitted of murder in the death of her daughter Caylee. The Florida sheriff's office that investigated Caylee Anthony's death confirmed Sunday, Nov. 25, 2012, that it overlooked a computer search for suffocation methods made from the little girl's home on the day she was last seen alive. (AP Photo/Red Huber, Pool, File) less In this Sunday, July 17, 2011 file photo, Casey Anthony, front right, walks out of the Orange County Jail with her attorney Jose Baez, left, during her release in Orlando, Fla., after being acquitted of murder ... more Photo: Red Huber, Associated Press Photo: Red Huber, Associated Press Image 1 of / 1 Caption Close Key Casey Anthony evidence missed 1 / 1 Back to Gallery

Orlando --

The Florida sheriff's office that investigated the disappearance of Casey Anthony's 2-year-old daughter overlooked evidence that someone in their home did a Google search for "fool-proof" suffocation methods on the day the girl was last seen alive.

Sheriff's Capt. Angelo Nieves said Sunday that the office's computer investigator missed the June 16, 2008, Google search. The agency's admission was first reported by Orlando television station WKMG. It's not known who performed the search. The station reported it was done on a browser primarily used by Anthony, who was acquitted of the girl's murder in 2011.

Anthony's attorneys argued during trial that she helped her father, George Anthony, cover up the girl's accidental drowning in the family pool.

WKMG reports that sheriff's investigators pulled 17 vague entries only from the computer's Internet Explorer browser, not the Mozilla Firefox browser commonly used by Casey Anthony. More than 1,200 Firefox entries, including the suffocation search, were overlooked.

Whoever conducted the Google search looked for the term "fool-proof suffication," misspelling "suffocation," and then clicked on an article about suicide that discussed taking poison and putting a bag over one's head.

A computer expert for Anthony's defense team found the search before the trial. Her lead attorney, Jose Baez, first mentioned the search in his book about the case but suggested it was George Anthony who conducted the search after Caylee drowned because he wanted to kill himself.

Not knowing about the computer search, prosecutors had argued Caylee was poisoned with chloroform and then suffocated by duct tape placed over her mouth and nose. The girl's body was found six months after she disappeared in a field near the family home and was too decomposed for an exact cause of death to be determined.

Prosecutors presented evidence that someone in the Anthony home searched online for how to make chloroform, but Casey Anthony's mother, Cindy, claimed on the witness stand that she had done the searches by mistake while looking up information about chlorophyll.

Prosecutor Jeff Ashton told WKMG that "it's just a shame we didn't have it. This certainly would have put the accidental death claim in serious question."