Deputy who shot 13 year old is a firearms expert?

There is something really, really wrong here. This report says the Deputy that shot this teenager was a "firearms expert." So how is it he didn't know the kid's gun was plastic?

Sonoma County Deputy ID'd Who Killed Andy Lopez, 13, as Erick Gelhaus
NBC News
By Lisa Fernandez
Tuesday, Oct 29, 2013

The Sonoma County sheriff's deputy who fired the shots that killed a 13-year-old boy carrying a replica assault rifle last week is a firearms expert, Iraq War veteran, and a regular contributor to magazines and blogs, where in one article, he wrote about needing to have a "mean gene" to stay alive in the "kill zone."

The Santa Rosa Press Democrat first reported the name of the deputy as Erick Gelhaus, 48, which was confirmed to NBC Bay Area on Monday by Assistant Sheriff Lorenzo Dueñas. In a November 2008 SWAT Magazine article titled "Ambush Reaction in the Kill Zone," (PDF) Gelhaus wrote that in order to stay alive, you must take action and have a necessary "mean gene."

"If you cannot turn on the "Mean Gene" for yourself, who will?" Gelhaus wrote in a training article to teach law enforcement not to get killed while encountering an ambush.

Gelhaus' partner, a new hire with 11 years experience, did not fire his weapon, investigators said, and his name has not been publicly released.

Gelhaus and the other deputy were placed on paid administrative leave. Sheriff's officials said he has never fired upon a suspect before. Gelhaus did not return repeated calls to the Press Democrat for comment.
read more here