Thanks, That's interesting. I didn't know you are a ranger. So what would you do if you saw a tagging in progress? I mean can you arrest them on the spot?
What's to stop a rival gang from tagging the others moniker? 
I am one of the Volunteers working for the USFS out of the Big Pines Station. For the most part there are three "branches" of the USFS that most forest visitors come into contact with. Recreation, Fire and Law Enforcement. As Volunteers for the USFS we work in "Recreation". We are the face of the Forest Service before the public. We are the good guys, the rangers you remember when growing up. We take care of the campgrounds and trails. We are there to answer questions, inform the public of and enforce various Forest regulations, and pass out Smokey Bear comic and activity books to the kids. Should we encounter an injury, we call in the Paramedics. If we encounter a crime in progress, we call in the LEOs.
Part of our training dealt with how to handle situations and keep ourselves out of harms way. Our training is always ongoing and "people skills" are very important. We rarely work alone and we do not put ourselves in dangerous situations or where we might run into serious problems with unsavory characters. We have LEOs (Law Enforcement Officers) Federal Police, if you will, who patrol the area as well and work with us. It is their job to cite lawbreakers and make arrests.
Just a couple of weekends ago when we were responding on a illegal campfire that was off the beaten path, in an area where we've had problems with illegal shooting, we called in for assistance from "Edwards-17" (LEO) and a LACo Sheriff's 260-Roberts unit. It really wasn't needed but they were in the area, so why not? It is better to be safe than sorry. You never know who you're going to run into in the woods. I kind of felt sorry for the guy. He just wanted to get away from all the commotion in the campgrounds by the Hwy, and here comes a USFS Blazer, a Federal Law Enforcement Cruiser and an LACo Sheriff's rig. The only ones missing were the CHP and the FBI.
The LEO ran his license for wants and warrants and we had him put the illegal campfire out. He could have been cited, but hey, we are not out there to ruin people's day. We gave him suggestions on where to camp where he could have a campfire legally and bid him a good day.
Should we observe tagging going on, or something more serious like individuals with guns, we'd observe, keep ourselves out of harms way, contact Angeles Dispatch and have them bring in the people who can handle it. It's hard to out run the radio.
As for someone else using another's moniker, that kind of defeats the purpose of their tagging in the first place. They want THEIR moniker made known. In the case of a tagger being charged with ALL the occurrences of it, I doubt he did it all himself, as there are other members of the "gang", but he's the one that got caught. Hey, it's a risky business.