Second-Degree MurderPlea - KULR-8 Television, Billings, MT

Second-Degree MurderPlea

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A Saint Xavier woman charged with second-degree murder of a three-year-old girl is set to change her not-guilty plea Thursday.

According to court documents Mary Agnes Leider wants to lessen the charge she's facing in connection to the death of Tenielle Big Day.

Big Day was found dead next to Highway 313 on December 3, 2012.

Prosecutors in the case say Big Day was on Leider's lap when Leider allegedly opened the passenger door and threw Tenielle onto the highway.

Court documents say Leider was allegedly with Big Day and her two brothers out partying the night before.