FORT WAYNE, Ind. (AP) — A woman whose father and son were killed in an interstate crash nearly a year ago is asking anyone who witnessed the incident to come forward.

Pam Shelmadine's father, Blaine Miller, and her son, Jeff Shelmadine, were killed July 11 when their broken-down semitrailer was sideswiped by another truck on Interstate 69. A third man also died of injuries suffered in the crash.

Prosecutors tell The Journal Gazette that they don't have enough evidence to file charges against the Michigan man who was driving the other semi.

Prosecutors say it's hard to press criminal charges in fatal crashes if there is no obvious wrongdoing by the driver. Indiana lacks a negligent homicide statute.

Miller and Jeff Shelmadine were well-known in Indiana racing circuits.