After poor-performing worker complains about e-mail, should we follow through on plans to fire?

Q. Admittedly, this is an odd-ball question. My HR department just received a complaint from an employee about risqué e-mails that some of her co-workers were trading back and forth. Coincidentally, the employee who complained is also slotted for termination because of poor performance and attendance problems. Is there any risk in terminating this employee in light of her recent complaint?