KALISPELL, Mont. - It's been four years since Kalispell resident Nicole Waller went missing in western Montana.
This year a judge sentenced her former boyfriend, Cody Wayne Johnston, to life in prison for her murder.
Sunday NBC Dateline will take us inside the search for Waller and her killer.
According to court documents Waller went missing after a trip to eastern Montana to visit her then-boyfriend Johnston.
The documents state that Waller's sister, Carmen Keibler, received a text from Nicole on Feb. 13, 2013, at 9:27 p.m. saying she would be returning home the following day.
Keibler said the next day she got a phone call from Johnston that Nicole had left, and he had turned off her phone since it was under his account and he would no longer contribute.
When Waller never returned home Keibler told NBC Montana in a previous interview, "My mom and I called every hospital, clinic, any place we could think of from here to North Dakota just trying to see if maybe something had happened and she wasn't able to contact us herself."
Johnston was charged in August 2015, convicted in October 2016 and sentenced this January to life in prison, plus 10 years for being found guilty of a tampering with evidence charge.
Charging documents state Waller's car was found abandoned in Poplar with two live guinea pigs belonging to Waller's daughter in the car.
Investigators believe after Johnston murdered Waller he hid her body in a barrel. They haven't been able to find the body.
Keibler previously told us, "I'm not going to give up. You know, I hound the law enforcement agencies all the time. What's new, what's going on."
To read Johnston's affidavit, click here.