Matthew Nelson, 32, had no comment as he left the Vista Courthouse on Monday, and he is now facing the possibility of jail time.
A judge rejected the plea deal agreed upon by both sides, and the case could potentially go to trial.
The victim's parents remain hopeful for justice.
"We were thinking he may actually go to jail. I think they thought they were going to let him off with nothing, and now he might actually do some jail time," they said.
It was back in March that Sheriff's said the former Country School employee was caught on surveillance cameras stealing the student's Ritalin tablets and replacing them with Claritin.
According to the student's parents, their child is allergic to Claritin.
"That is what he would usually take. It was replaced with this white one. They look almost alike," said the parents.
Fortunately a new bottle of the pills they had received from the pharmacy had a slight green tint to it. School officials realized after one dose, something was not right.
The student's parents believe that if the medicine had not been green, they might not have caught it.
According to Sheriff's, Nelson confessed once he was confronted. He admitted he had a drug problem and checked himself into rehab.
He faces charges of felony burglary and misdemeanor counts of child endangerment and petty theft.
The student's parents said they are still waiting for a chance to address Nelson in court, and if there is a trial, then so be it, they said.