reporter: this is emerson ferreira. he lives here in jardim santa lucia, about an hour's drive from sao paolo. he's 29 now, and spent five years in jail. he turned to drug dealing as a way out of poverty, and was caught with half a kilo of marijuana. emerson: in jail we had a lot of people liviving in a very smal cell. thinings turned viviolenty quickly. you feelel like an animal whwn you're in jail, , and you dont think about changing. the whole punishment system is supposed to ensure that criminals can be reintegratetd and becomeme part of society again. but when you treat peoeople lie animimals in j jail, it makes m more violelent once they're ot again. reporter: emerson's been out since 2012 and now finds it easy to talk about the experience. he was still behind bars when he made the decision to turn his life around. and he started as soon as he was out. he lives with his girlfriend. he gives lectures on his criminal past, vividly describing whahat he did wrongn his life. global shapers approached him, and he joined