EDMOND, Oklahoma - It's been one year since 16-year-old Piedmont teen Anne Hill went missing. Her mother Lori and family friends marked the somber anniversary with an event Saturday morning and afternoon at Fink Park in Edmond. 

Anne Hill was on scholarship at a prestigious private school in Oklahoma City when she disappeared last April 11. Lori Hill said her daughter took a college entrance exam when she was in the seventh grade, and did so well, she would have qualified then to go to OU and OSU. Anne Hill had a bright future. 

But on April 11, 2014, court documents alleged Anne Hill was watching movies at the Edmond apartment of a suspected drug dealer with other teens. Now, 17-year-old Chadd Raymond has already pleaded guilty to Hill's murder. 

Chloe Thomas, 17, was charged as an accessory. Thomas told investigators Raymond strangled Anne Hill as she attempted to leave that apartment next to Fink Park. Thomas told investigators she helped Raymond bury Annie Hill's body in a shallow grave in a rural area next to a highway. 

The problem is, they've had a hard-time figuring out which highway. 

Darcie Parton-Scoon is a private investigator who's been working with Anne Hill's family. “We have gone through multiple grid searches throughout all of Edmond, north Edmond, east Edmond. We've done grid searches on I-40, I-35, for about 200 miles.” Scoon said the family is looking for help in hiring cadaver search dog teams. “That is crucial, because dogs search 500 times faster than humans, and much more thoroughly. So that is one thing that they need,” she said. 

Lori Hill was at the event Saturday at Fink Park. But she chose not to say anything publicly.