How She Did It: Gruesome Autopsy Reveals NASCAR Star Jimmie Johnson's Nephew Shot in Head and Chest By Grandmother in Murder-Suicide

The young nephew of NASCAR legend Jimmie Johnson was brutally shot in the head and chest by his grandmother who went on a shocking shooting spree, killing her husband before taking her own life, RadarOnline.com has exclusively learned.

Johnson’s mother-in-law, Terry Lynn Janway, went on the shooting spree on June 26 inside the family’s Oklahoma home after authorities received a brief 22-second phone call from an unhinged woman who chillingly stated: “There is somebody here with a gun.”

Responding officers found, Dalton Janway, 11, dead with “gunshot wounds to the head and chest” while his grandfather, Dr. Jack Lee Janway, 69, died from a single gunshot wound to the chest, according to the documents released by Oklahoma’s Office of the Chief Medical Examiner.

Both of their deaths were ruled a homicide. Terry suffered from a self-inflicted gunshot wound to the chest that was ruled a suicide, the documents revealed.

The report also stated the distraught grandmother suffered from “blunt force injuries” and that the toxicology report indicated she was not under the influence of alcohol or drugs at the time of the shooting that rocked the NASCAR community.

The seven-time NASCAR champion has been married to Janway’s daughter, Chandra, since 2004, and they share two children. Johnson withdrew from the NASCAR Cup race in Chicago following the shooting in Muskogee, about 50 miles southeast of Tulsa.

The motive for the shooting remains unknown, but published reports have indicated Chandra’s mother battled depression and was tragically unable to cope with the skydiving death of her 27-year-old son, Jordan, in 2014.

Jordan was unable to open his parachute after a mid-air collision with another skydiver. His emergency chute failed to deploy, according to a report in USA Today.

After the police were alerted to the home by the 911 caller, the dispatcher asked, "Do you know who this person is?" But after hearing silence, he again inquired, "Do you know who it is?" before the caller hung up.

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Responding officers spotted one victim dead in the hallway of the home and heard another gunshot go off inside the house, where two other bodies were discovered.

"The Johnson family has asked for privacy at this time and no further statements will be made," Legacy Motor Club said in a statement after the unfathomable tragedy.