Messages on the day of a fatal collision were deleted from the cellphone of a motorist who has now been cited in connection with the crash, according to forensic analysis of the phone that the driver kept for weeks afterward.

Heidi L. Butau, 45, of Braham, Minn., was charged Monday in Chisago County District Court with one offense, a misdemeanor for failing to obey a stop sign northeast of Cambridge on Dec. 10 before her car struck the one being driven by 75-year-old John C. Ploetz, of nearby Harris.

If convicted, Butau's maximum sentence would be 90 days in jail and a $1,000 fine.

Butau was charged by summons. She did not return calls seeking comment Tuesday.

Butau has been convicted in Minnesota eight times for speeding, twice for driving with a suspended license, twice for having expired vehicle tabs and once for running a stop sign. Her license was valid on the day of the crash and remains so, the state Department of Public Safety said.

She also has been convicted at least twice for texting while driving, most recently on Interstate 394 in Minneapolis on Nov. 16, 3½ weeks before the fatal collision. In that case, she was "clearly distracted and [had her] eyes off the road" while looking up a phone number, according to the State Patrol citation.

On the day of the crash, Butau told a sheriff's deputy at the scene that all she remembered was driving on Acacia Trail and "then the crash occurred" at Stark Road, the criminal complaint read.

A day later, Butau "adamantly denied using a cellphone" or being distracted, the complaint continued. She volunteered that she called her daughter shortly before the crash, then placed the phone in a pocket or vehicle storage area, where it remained until after the collision, an additional court filing read.

Butau offered to allow deputies to go through her cellphone at the scene, according to a search warrant made public Tuesday. One deputy said a time would be arranged.

When asked why more than two weeks passed between the crash and when the phone was taken for inspection, Sheriff's Capt. Keith Hoppe said Tuesday, "In general, a cellphone is not taken as part of a normal crash investigation," and a witness to the crash made "no mention of cellphone usage or distraction."

After a sheriff's investigator retrieved Butau's cellphone on Dec. 26 for inspection, analysis revealed that "all messages prior to [the date it was turned over] were deleted," the charging document read. "Due to most of the data being deleted," [the investigator] could not make any determination on cellular phone usage at the time of the crash."

Asked by an investigator about the deleted data, Butau said that "she routinely erases her messages and calls, and is very 'anal' about organization," the search warrant read.

The investigator later received records from the phone's service provider, AT&T. However, a review of those records left him "unable to determine with certainty that [Butau] was using the device at the time of the crash," according to the complaint.

At the time of his death, Ploetz was the longtime commander of Harris American Legion Post 139. He had owned a Rush City trucking firm with his wife for 30 years until 2005. He is survived by three children and seven grandchildren.

Ploetz's wife of 48 years, Joanne, said she expected that Butau would not face a more serious charge after learning about the deleted phone data.

Ploetz was traveling to Arizona Tuesday, and she packed the investigative file on her husband's death to take with her.

Before arriving at the Minneapolis-St. Paul International Airport, she said, "I stopped at Fort Snelling [National Cemetery] and saw him ... It's my first trip without him."

Paul Walsh • 612-673-4482

Joanne and John Ploetz (The Minnesota Star Tribune)