The Las Vegas Metropolitan Police Department worked with the National Center for Missing and Exploited Children to develop the portraits, which are based off images provided by the medical examiner and depict the face of a young Hispanic boy with black hair and brown eyes.
Police said the boy appears to be between the ages of 8 and 10, is 4-foot 11-inches tall and weighs 123 pounds.
Authorities have asked local teachers, in particular, to pay close attention to the new images.
The Federal Bureau of Investigation is now offering a reward of up to $10,000 for information leading to the identification of the boy, whom authorities are calling John "Little Zion" Doe, or the identification, arrest and conviction of the individual responsible for his death.
"This child has the right to be referred to by his given name. He's someone's son, someone's grandson and he deserves law enforcement's commitment to solving this case," FBI supervisory special agent Jeremy Schwartz said during a press conference Thursday. "We are counting on the public to help us with his identification."
Police said the boy's body was discovered by hikers near a forest area off the Mountain Springs Trailhead, southwest of Las Vegas, on the morning of May 28. Due to the location where the body was found, police believe the boy may have lived in Las Vegas, Pahrump, Baker or other nearby cities.
Authorities have not yet disclosed how the boy died, but Lt. Ray Spencer of the Las Vegas Metropolitan Police Department told reporters that he was "murdered and left."
"I'm confident that we are going to find the person who is responsible for committing this horrible act and leaving him out in Mountain Springs," Spencer said during Thursday's press conference.
Spencer said investigators won't be able to identify the victim or a suspect "without the public." Police detectives are working with multiple community, state and federal partners, and they have already received "several hundred tips" in connection with the case, according to Spencer.
"We are literally identifying any potential leads regarding who the deceased is," he told reporters. "We are going door-to-door looking to make sure on every one of those tips, that the children that someone has called in, we are verifying their wellbeing."
Anyone with information concerning the case is urged to contact the Las Vegas Metropolitan Police Department's homicide unit at 702-828-3521 or the FBI's toll-free tip line at 1-800-225-5324.
"Any tip, regardless of how small, we are following up on in an effort to identify who he is," Spencer said.