Coworker leaving crack at work

So I through out like four crack pipes. I thought they was customers cuase I found them on shelves or near the products. However now am finding it in the bathroom, garage and in the cleaning supply's. Which is also contaminating cleaning supply's. I scared of accidentally finding it during a customer coming in and then calling the police. Manager says they not sure who it is and I not 100% either. But we not supposed to be doing substances while at work but also not 100% who it is. Just that it keeps showing up.