Robert was last seen at approximately 8:45 a.m. on July 6, 1990 in the vicinity of the 13500 block of south 8th Street in Colorado Springs, Colorado. He was staying at Cheyenne Mesa, a day program and residential treatment facility for adolescents with psychiatric and behavioral problems. According to his mother, he was traumatized after he witnessed his stepfather's suicide when he was seven.

The morning of his disappearance, Robert called his mother and insinuated that something was wrong, but told her he could not say exactly what was troubling him because the call was being monitored. His mother immediately called the facility to make arrangements to visit him, but was told that Robert was on an outing. Later the day, a Cheyenne Mesa employee told Robert's mother he had run away. He has never been heard from again. He had been at the facility for only a few weeks prior to his disappearance.

There is some confusion as to what Robert was last seen wearing. His mother was told he was wearing a blue shirt and black trousers, but these clothes were returned to her along with the rest of his belongings. She stated he brought two pairs of shoes to Cheyenne Mesa and she got both pairs back, indicating he may have been barefoot.

Authorities are not certain what happened to Robert. He has no history of runaway behavior, and his mother stated that even if he had run away, it would be highly unusual for him to have no contact with his loved ones for this long. Robert's mother had a close relationship with her son at the time he went missing. There is no evidence of foul play in his disappearance. His case was reclassified to a runaway to endangered missing several years after his disappearance; it remains unsolved.

Cheyenne Mesa closed in 1997, owing to financial insolvency.