( CNN ) -- Police arrested a former Creighton University medical resident Monday for two double homicides over five years , both sets of victims were connected to the pathology department at the Nebraska school . Anthony Joseph Garcia , 40 , was arrested during a traffic stop in Illinois , Omaha Police Chief Todd Schmaderer said . Officers were making preparations to arrest him Tuesday , but the Indiana resident `` became mobile '' and police felt they needed to arrest him right away , he said . Garcia was arrested on four counts of first-degree murder in the May deaths of Roger and Mary Brumback , both 65 , and the March 2008 deaths of 11-year-old Thomas Hunter and his family 's housekeeper , Shirlee Sherman . All lived in Omaha . Roger Brumback was a professor in the pathology and neurology departments at Creighton and announced his retirement shortly before he was killed . Thomas Hunter 's father , Dr. William Hunter , is a faculty member in Creighton 's 12-person pathology department . The boy 's mother , Dr. Claire Hunter , is an associate professor in Creighton 's cardiology division . Garcia was a resident who worked in the pathology lab from July 2000 until June 2001 , when the Brumbacks and William Hunter fired him , the university said . Neither police nor the university said why Garcia was terminated , but CNN affiliate KETV said it was because of `` erratic behavior . '' An Omaha task force had been monitoring Garcia `` for some time , '' Schmaderer said . He was pulled over for suspected alcohol impairment and was found with a .45 handgun . Authorities believe Garcia acted alone , Schmaderer said . It 's not clear where Garcia was working at the time of his arrest . `` Creighton University and particularly the School of Medicine and Department of Pathology are grateful for the work of the Omaha Police Department and the special task force in these investigations , '' the school said in a statement late Monday . CNN 's Dave Stewart contributed to this report .
Thomas Hunter 's worked at the KETV pathology lab . He was arrested in the deaths of four people tied to the school . A professor and his wife were killed in March 2008 . The son of four professors was killed in May along with their housekeeper .