dr. nguyen. dr. nguyen told us he'd been to six workshops or conferences that ran from two to four days long and participated in two other one-day laser courses. >> be careful with that prescription. >> reporter: he agreed to meet with us at his spa. so what happened? what went wrong? >> so my best estimate is that agent got outside of the lesion. >> reporter: it seems to me it would be clearly a mistake. >> not necessarily just because bruising has occurred doesn't mean that it's a mistake. >> reporter: so you stand behind the work? >> i do standby that. >> reporter: and you think that the seminars that you've attended provide enough training to be able to do these really tricky procedures on people's faces? >> so it's the same training that even dermatologists get after they graduate. >> reporter: that's misleading, says this doctor. after graduating from medical school dermatologists have three years of intense training to treat the skin. >> you don't learn this in a weekend. >> reporter: as for st