Matt McCallister is being held in the Marion County jail in Indianapolis. A probable cause affidavit suggests McCallister is the man who allegedly pulled the trigger, killing Joseph Nelson of Martinsville.
Jade Stigall, 22, and David Lackey, Jr., 30, both of Boonville, and Shawn Grigsby, 22, of Evansville were previously arrested in connection with the slaying. According to the affidavit, McCallister and Stigall are siblings.
Play the above video to see more details revealed in the affidavit obtained by Eyewitness News.