Another use for placebos in medicine

(Allegedly) trying to cover up drug crimes.  By a pharmacist (allegedly).

Monday, investigators reported more details of the searches. They said they found expired bottles of oxycodone and OxyContin, set for destruction, that were filled with M&M’s candy. The bottles had been resealed to appear unopened.

I suppose they don’t open the bottles of expired meds?  Then how are they disposed of?