TACOMA, Wash. (KOMO) -- A Graham man plead guilty Thursday to murdering Nicole White, a 28-year-old mother of two who was killed in June 2015.

Jonathan Daniel Harris pleaded guilty to second-degree murder. In a plea agreement, the charged was reduced from first-degree murder. Prosecutors want a 26-year sentence. He will be sentenced Sept. 23.

He was accused of killing White, then dumping her body near Joint Base Lewis-McChord. The forensic anthropologist determined White had severe facial, chest and arm fractures, and the injuries are consistent with being stomped.

"There's something obviously wrong with him if he can beat someone to death," said White's sister, Melisa Nieto.

Court documents say Harris killed White after they went on a date. The two were seen at the Jeepers Bar and Grill in Spanaway by witnesses. A woman who identified herself as the victim's sister says the two previously had several dates in the company of other people, but the last date was the first one White and Harris had by themselves.

As part of his plea agreement, Harris has agreed to tell police about what happened the night he murdered White.

"He's going to say what happened, so I think for closure for the family it's going to be better," Nieto said.

Harris was arrested after investigators used his cell phone records and an ignition interlock device on his truck that takes a picture. Investigators used a picture the device took when Harris blew into the device to track down the location where White's body was found two weeks after the two were last seen.

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