In June 1977, shortly before his 13th birthday, he beat the family dog to death with a baseball bat and told his parents the animal had been fatally injured in a fall.
He was trained as a radio operator at Marine Corps base in Twentynine Palms and then served in Desert Storm.
At Saddleback Community College in Mission Viejo, California, he stalked 23-year-old communication arts student Robbin Brandley and stabbed her 41 times with a knife.
Two months later, Urdiales struck in San Diego, killing 31-year-old Mary Ann Wells, whose body was found by police on September 25, 1988, in an abandoned warehouse.
[citation needed] In 1991, he was honorably discharged from the Marine Corps and moved back to his parents' home in Chicago.
As he drove, Urdiales confronted the young woman about the fake phone number and began to assault her, tying her hands and cutting off her clothes.
[citation needed] As a security guard in a Chicago mall, he enjoyed great trust among customers in the family friendly environment.
On July 14, 1996, police found the body of 21-year-old Cassandra Corum in the Vermilion River in Livingston County, Illinois.
[citation needed] In December 1996, Urdiales was arrested for possession of an unlicensed weapon but was released after paying a fine.
[3][2] Urdiales was arrested on April 23, 1997, when the police wanted to check his gun in connection to the ongoing series of murders.
The subsequent lab tests supported Urdiales' confession and his involvement in the murders of Ulyaki, Corum and Huber.
After a study by Northwestern University concluded that some death row inmates had been innocent, and that innocence no longer could be judicially recognized, then-Governor of Illinois, George Ryan, determined on January 11, 2003, that all 167 people sentenced to death in Illinois at that time would have their sentences commuted to life imprisonment.
[10][11][12] On Friday, November 2, 2018, at around 11:15 PM, Urdiales was found unresponsive in his cell in the Adjustment Center of San Quentin State Prison.