An investigation into a workplace shooting at a Lockheed Martin plant in July that left seven people dead, including the gunman, has ended. A Lauderdale County grand jury recommended closing the probe Friday after meeting with Sheriff Billy Sollie, who headed the investigation, for 1-1/2 hours. Doug Williams left a meeting at the plant on July 8 and returned with a shotgun and rifle. He killed six co-workers and injured nine others before committing suicide. "We feel 100 percent that he acted alone and that he acted because of anger he had against the Lockheed Company, where he thought he was being treated badly," District Attorney Bilbo Mitchell said. The jury did not return any indictments in the case, and Sollie said he didn’t anticipate any. "We believe the grand jury heard the evidence and their decision is the correct one," Sollie said. Sollie has said he wanted the district attorney’s office to present the findings to help put to rest questions about Williams’ motive. He also wanted to address concerns raised by U.S. Rep. Bennie Thompson, D-Miss., who asked federal authorities to investigate whether the shootings were linked to domestic terrorism because the majority of people killed were black. The U.S. Occupational Safety and Health Administration found no culpability on Lockheed Martin’s part. Details of the investigation into the shooting have not been released, but Sollie said he could be ready to publicly discuss the investigation and its findings within the next couple of weeks. Sollie said he believed lawsuits dealing with the shooting will likely tie up the courts in the future. "We know that members of our department will be in a courtroom somewhere for the next decade. So it’s not over," Sollie said. (Source: Associated Press)