Shayna Ritthaler

In court, the defendant referred to the victim as his girlfriend.

The prosecutor has said the suspect shot Ritthaler after an argument.

Investigators are trying to determine how the two met.

He says among other things, the victim's and defendant's cellphones are being examined for possible clues.

Other students had reported to school administrators that Ritthaler was last seen walking toward the Coffee Cup.

Meade County Sheriff Ron Merwin said he couldn't yet share details on how the girl died.

Ritthaler was last seen shortly after 12:30 p.m. Thursday getting into a dark-colored vehicle at the Coffee Cup in Moorcroft.