Pennsylvania's state police agency is trying to shut down a grand jury looking into its policy of investigating line-of-duty shootings by its own troopers.

State police lawyers will be in court this week to argue the grand jury has no right to exist, let alone weigh in on whether Pennsylvania State Police should use outside law enforcement to probe shootings by troopers. Experts say police shooting investigations should be independent to ensure objectivity.

By seeking to silence the grand jury, experts say the agency is inviting criticism that it's trying to avoid scrutiny.

University of Pittsburgh law professor David A. Harris says the state police attempt to squash the grand jury probe shows a "tin ear" at a time of heightened national concern over fatal police shootings.