La Crosse County prosecutors say they will argue that heavy debt caused Lepsch to fatally shoot Paul Petras and his 19-year-old son, A.J. and steal merchandise at May's Photo in La Crosse last September.
The 40 year old Lepsch has denied any involvement in the slayings. Authorities say Lepsch needed money to pay a $60,000 judgment against him in a 2003 theft case.
Lepsch is charged with two counts of first-degree homicide, armed robbery with the use of force and illegal possession of a firearm. Testimony is expected to begin Wednesday following opening arguments.