Bristlenose pleco eating tank mate?

I woke up today and my dalmatian molly was dead, there was a huge chunk out of him and his eyes were gone. My tank is 10 gallons, and the only other 'big fish' in there was 2 other male mollies (that have been together for 2 months without problems) a columbian tetra, and a female swordtail. I know plecos are suppose to be peaceful, so did my fish just get in the way of his eating?