Welsh, 21, was allegedly shot eight times by Chad Richards, a 23-year-old former college wrestler, in her off-campus apartment in Whitewater, Wisconsin, according to court records.
Police say 29-year-old Terry Lewis Taylor, Jr., was intentionally and fatally struck with an SUV driven by 22-year-old groom James Shirah.
Owens was convicted in the murder of 41-year-old store clerk Irene Graves during an armed robbery in Greenville County, South Carolina.
Although he is being held at a youth detention center, Gray, 14, will be tried as an adult on four counts of felony murder for the deaths of fellow students Christian Angulo and Mason Schermerhorn, both 14, and teachers Christina Irimie, 53, and Richard Aspinwall, 39.
