Missing from the mall: How investigators nabbed a serial rapist in the death of a college student

"20/20" explores the investigation into the 2003 murder of Dru Sjodin, who went missing from a North Dakota mall after clocking out of work.

More than 20 years ago a North Dakota town was shaken after a college student went missing after she left the mall where she worked at the beginning of the busy holiday season.

Dru Sjodin's disappearance in November 2003 banded together several of her friends, family, and neighbors in two states along with multiple law enforcement agencies.

And although their search ended in tragedy, her family was able to get justice and spark change to make it easier for the public to track sex offenders living in their communities.

A "20/20" episode airing Jan. 12 at 9 p.m. ET and streaming on Hulu the next day takes a look at the case with interviews with key investigators, Sjodin's family, college friends, and others.

Dru Sjodin, 22, who was a senior at the University of North Dakota studying graphic arts, was leaving her job at the Columbia Mall in Grand Forks on Nov. 22, 2003. After buying a purse at one of the stores, she walked to the parking lot and was on the phone with her boyfriend Chris Lang, according to investigator Bill Macki.