After Chris Watts' arrest for killing his family, his girlfriend conducted internet searches about Amber Frey, who was Scott Peterson's mistress

As police focused on killer Chris Watts after his pregnant wife and two young daughters disappeared and were found murdered in August, the woman with whom he was having an affair wondered if she’d be publicly shamed, conducting internet searches about the mistress of another infamous killer.

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Kessinger’s Internet searches about Frey on Aug. 19 — four days after Watts was arrested in the Aug. 13 disappearance of his family — also included queries about a book deal Frey obtained, along with Frey’s net worth, according to documents in the Watts investigation released last week by the Weld County District Attorney’s Office and obtained by PEOPLE.

Image zoom RJ Sangosti/The Denver Post/Getty; Inset: Weld County Sheriff's Office

When Kessinger revealed her identity to the media in an interview with the Denver Post after Watts pleaded guilty to killing his wife of nearly six years, 34-year-old Shanann Watts, and their daughters, Bella, 4, and Celeste, 3, Kessinger said she “barely knew him” and “we had just met.” She said the two co-workers had begun a physical relationship in early July but were taking it slow and didn’t discuss long-term plans. She added that Watts told her he was in the process of finalizing divorce before later telling her the divorce had been completed.

The new documents provide further context for that claim.

On July 24, Kessinger Google-searched the phrase “Man I’m having affair with says he will leave his wife.” And on Aug. 8 Kessinger searched Google on topics relating to “marrying your mistress,” the documents show.

The records also reveal that authorities who examined Kessinger’s phone found hours-worth of searches for “Shanann Watts” and, after the murders, a search using the phrase “can cops trace text messages.”

The documents show Kessinger cooperated with authorities after Shanann and her children were reported missing by a family friend, although Kessinger initially acknowledged that she had deleted all of Chris Watts’ information from her phone before meeting with police.

Image zoom Chris Watts, Shanann Watts and their daughters Facebook

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Watts’ wife and two daughters had been dead only a few hours when — in the brief window between murdering them and coming under the suspicion of police — he took the time to look up the lyrics to a Metallica song, according to the documents.

The song he Googled, “Battery,” includes the lyrics “Smashing through the boundaries, lunacy has found me” and “Pounding out aggression, turns into obsession/Cannot kill the battery/Cannot kill the family.”

Colorado prosecutors said he strangled Shanann before sunrise in their Frederick home on Aug. 13, smothered the couple’s two daughters, and hid all three bodies on property owned by his then-employer.

Image zoom Chris Watts, at left, with Shanann Watts

The newly released documents flesh out the narrative that Watts, 33, had grown distant from his family and infatuated with Kessinger, with whom he wanted a “fresh start,” prosecutors said at his sentencing last Monday.

Surveillance video recorded him leaving his home about 5:30 a.m. on Aug. 13 to dump his victims’ bodies, less than four hours after Shanann had returned from a weekend work trip.

About 10:10 a.m. that same day, Watts went online to look up the Metallica lyrics, according to the newly released documents. By that point, his wife had already missed a doctor’s appointment — an unusual absence that raised the concerns of a friend who in turn alerted police, eventually leading to Watts’ arrest.

Watts exhibited other strange behavior before his arrest, authorities have said, including calling his girls’ school to say they would not be attending the upcoming year and contacting his realtor about selling his home.

Among the revelations in the new documents are text messages between Shanann and Chris, and Shanann and a friend, that show the strain in their relationship in the weeks before the murders.

On Aug. 7, six days before she was killed, Shanann shared with a friend that she was concerned Chris had pulled so far away from her that he may never return.