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ST. LOUIS (KTVI) – Police and prosecutors in the case against Pam Hupp are very interested in a knife that came from somewhere you might not expect.

It’s one of several new clues we discovered in a court document listing witnesses and addresses for Hupp’s October murder trial. Fox 2 obtained the record exclusively, with our partners at the St. Louis Post-Dispatch.  One of the addresses takes us to the unusual place police believe Hupp may have purchased a knife.

On the August day Hupp shot and killed Louis Gumpenberger, she claimed he was trying to kidnap her while using a knife.

After Hupp’s arrest for murder, later that month, St. Charles County Prosecutor Tim Lohmar said investigators traced it.  Lohmar said, “We`re confident we know where that came from.”

O’Fallon police officers traced it to the O’Fallon Dollar Tree. Fox 2 uncovered the detail from court documents.

St. Louis Post-Dispatch reporter Robert Patrick said, “You walk in the store, hang a right and the knife is kind of there staring at you in the face.”

Reporter Patrick learned Hupp may have purchased several dollar items key to the case.  Patrick added, “And it appears that some of the items that were bought in the same transaction as the knife are similar to items that were found in Pam Hupp’s house.”

He says dollar pens and dollar notepads interest investigators because of the alleged ransom note prosecutors say was planted in Louis Gumpenberger’s pocket.

Prosecutor Tim Lohmar said during an August news conference, “The investigation revealed a hand written note and $900 of United States currency that was double bagged in a zip lock bag were located in each of Gumpenburger’s pockets.”

As we revealed in an earlier Fox Files investigation, police found a connection with that $900 cash and other money in Hupp’s home.

A CSI agent reported finding a hundred dollar bill in Hupp’s dresser with a serial number identifier matching those in Gumpenberger’s pocket.

A police officer wrote in the warrant “It`s extremely uncommon for two people who reportedly do not know each other, to individually possess $100 denominations…Which contain the same identifiers (and) serial numbers… In order.”

Pam Hupp’s attorneys did not respond to requests for comment on this report. A judge recently scheduled her trial for October 3.