The long-tailed weasel (Mustela frenata) is a generalist predator that feeds mainly on rodents and rabbits. However, predation on Peromyscus rodents has been reported mostly at the genus level and records are scarce. In April 2018, we made a field trip to Laguna Bélgica Educational Park, Chiapas, to capture, handle, and study mammalian wildlife species. We set 15 Sherman traps 5 m apart on a 70-m linear transect for one night. One male M. frenata was captured along with a dead Mexican deer mouse (Peromyscus mexicanus) in the same trap. The rodent had incision marks on the skull, indicating that it had been captured by the mustelid. This new data point enhances the existing information regarding predation habits of M. frenata on P. mexicanus in Chiapas and could elucidate the weasel's ecological role as a biological control on rodent populations.