CHARLESTON, W.Va. -- A man charged with killing Mingo County's sheriff is being investigated by federal prosecutors over his gun permit application.U.S. Attorney Booth Goodwin said Thursday that the investigation will focus on the form filled out by 37-year-old Tennis Melvin Maynard, including if he was truthful about his personal information.Maynard is accused of shooting Sheriff Eugene Crum last week as Crum ate lunch in a Williamson parking lot.Mingo County Prosecutor Michael Sparks has said Maynard wasn't allowed to own a gun but wouldn't disclose why. Maynard's father has said his son has mental problems and previously had been in an institution.Federal law prohibits the sale of firearms and ammunition to certain individuals with a history of mental illness.The Bureau of Alcohol, Tobacco, Firearms and Explosives is leading the investigation into the application, Goodwin said."Lying on the form is a federal crime," he said.Goodwin said investigators also will check for a possible violation of gun-possession law.Authorities haven't disclosed what year Maynard bought a weapon at a local gun shop after filling out his gun application. Sometime after that, Maynard was turned down when he tried to make additional purchases, Sparks said.In January 2011, the West Virginia Supreme Court debuted a database that links with the FBI's National Instant Criminal Background Check System, which federally licensed firearms shops use to determine if a prospective buyer is eligible to make purchases. The national system was established under the 1993 Brady Bill.The state database involves information on people who have been involuntarily committed to a mental institution, said Supreme Court Administrator Steve Canterbury. Court records on such cases are confidential under state code, he said.On Wednesday, Sparks said there was a delay at the state level in reporting information to the national database that would have disqualified Maynard from gun ownership."You can't delay reporting if something doesn't exist," Canterbury said. "We did not have a connecting system to NICS until 2011."County mental-hygiene commissioners are directed within 72 hours of an involuntary commitment to enter data that's automatically sent on to NICS.Data collected starting in December 2009 didn't appear in the database until early 2011.Before 2011, data reporting was considered voluntary, "but there was none," Canterbury said. "To the best of my knowledge, nobody was ever reported from West Virginia before January 2011."Canterbury said FBI data show that 139 people have been denied firearms purchases nationwide because of mental-health data submitted to the NICS system from West Virginia. That includes 120 people denied in West Virginia and 19 out of state.Maynard was shot and wounded by a Mingo County deputy after a chase following the April 3 attack on Crum. The West Virginia State Police said Maynard crashed his car into a bridge in his hometown of Delbarton, then got out and pointed a weapon at the deputy, who then shot him.The State Police has said Maynard is up and moving at a Huntington hospital. He is charged with first-degree murder and attempted murder.