Dec. 1 (UPI) -- Lawyers for Luigi Mangione are seeking Monday to have evidence gathered during his arrest thrown out in his trial for the alleged murder of UnitedHealthcare CEO Brian Thompson.

The 27-year-old is expected to appear in New York state court for the beginning of his pretrial on nine counts of murder and weapons charges. He pleaded not guilty to all charges, including four separate federal charges that could result in the death penalty.

Mangione is accused of fatally shooting Thompson, 50, on Dec. 4 on a Manhattan sidewalk as the latter was on his way to a UnitedHealthcare shareholder's meeting. Police arrested Mangione days later as he was at a McDonald's in Pennsylvania.

During his arrest, police gathered evidence from a backpack Mangione was wearing. Defense lawyers were expected to argue Monday that authorities illegally searched his bags without a warrant, and, therefore, the evidence is not admissible in trial, CNN reported.

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