Authorities didn't immediately know if the body belonged to Jade Morris, Las Vegas police homicide Capt. Chris Jones said.
However, Jones also said: "I can tell you that the likelihood is that this is our victim."
A passer-by called 911 about noon about a girl's body in a remote area near Dorrell Lane and North 5th Street, North Las Vegas police said. That's a short distance from the northern Las Vegas beltway and about 10 miles from downtown Las Vegas.
Jade was last seen by her family at about 5 p.m. last Friday with Brenda Stokes, police said.
Stokes was later arrested after she was accused of slashing a co-worker with razor blades at the Bellagio resort casino. Stokes, 50, is now in jail.
Police said she was a trusted friend of the girl's father, and was supposed to have taken the girl Christmas shopping at an outlet mall off Interstate 15 near downtown Las Vegas.
Stokes returned to another friend the red 2007 Saab sedan that she borrowed for the shopping trip, Jones said.
A short time later, Stokes was arrested at the Bellagio casino after allegedly attacking a female co-worker, Joyce Rhone, as Rhone dealt blackjack.
Stokes is accused of wielding a razor blade in each hand as she attacked Rhone, who was hospitalized with deep cuts on her face, including one from her ear to the edge of her mouth. A police arrest report said Rhone, 44, also had several smaller cuts around her right eye.
Records show that Stokes was being held Thursday on $60,000 bail at the Clark County jail on felony battery with a weapon, burglary and mayhem charges that could get her decades in prison.
She told a judge Wednesday that she had not obtained a lawyer. She is due again in Las Vegas Justice Court on Friday.
Jones said Thursday that Stokes has not cooperated with the investigation.
The arrest report says casino video shows Stokes attacking Rhone before a casino patron and security officers intervene. Officer Marcus Martin said the video is evidence that may be shown by prosecutors in court but will not be made public by police.
Police said Stokes later told investigators that she attacked Rhone over harassing phone calls and an unspecified betrayal that ended their seven-year friendship.
Stokes also told police she visited her doctor last week, seeking to be admitted to a hospital "due to feeling like she wanted to hurt someone."
She is reported to have told investigators she hadn't taken a prescription anti-anxiety drug on Friday, and that, "Sometimes people just snap."