A 33-year-old woman faces charges of first-degree murder and tampering with a corpse after she allegedly killed her brother in an attempt to gain control of a 700-acre ranch on prime Gunnison County land that’s worth millions, authorities say.

Stephanie Jackson is being held on $500,000 bond.

Gunnison County Under Sheriff Mark Mykol said authorities allege Jackson was responsible for the disappearance and death of her brother Jacob Henry Millison.

“It’s definitely ranch-related,” Mykol said Thursday of the ranch in Quartz Creek Valley. “It’s a beautiful setting. Indian Head Rock is on the property.”

Numerous officers from the Gunnison County Sheriff’s Office, Colorado Parks and Wildlife and the Colorado Bureau of Investigation arrested Jackson Wednesday afternoon on Gunnison County Road 76.

Jackson also faces charges of seven counts of accessory to first-degree murder and one count of abuse of a corpse, Mykol said.

Millison’s friends filed a missing person’s report at the sheriff’s office on May 25, 2015. Three months later, a family member also reported Millison was missing, Mykol said.

CBI agents, sheriff’s investigators, Gunnison police officers followed numerous leads. Authorities served a search warrant at 5291 Gunnison County Road 76 in mid-July, Mykol said.

About 67 officers including nine police dog teams spread out over the 700 acres and found Millison’s remains on the property, he said. Authorities confirmed several weeks later that the remains were Millison’s.

Mykol said the cause of death has been determined but he declined to divulge it while the investigation continues.

“The investigation was phenomenal,” said Mykol, adding investigators have spent more than 1,000 hours on the case. “We’ve spent the last eight months on this.”

Additional suspects also are under scrutiny, he said.