LOS ANGELES (KABC) -- For 12-year-old Alfonso Hoffman, a dream came true Wednesday morning as he was sworn-in as a Los Angeles County sheriff's K-9 deputy for the day.The Boyle Heights boy was diagnosed with leukemia earlier this year."He's actually the one who noticed some lumps on his neck," Desiree Hoffman, Alfonso's mother said. "Tomorrow he'll be hospitalized, so it's nice he can have some fun before he actually goes into the hospital."Alfonso is facing three years of cancer treatments."I'm really happy. I want to be a K-9 officer because I like handling with dogs," Alfonso said shortly after his swearing-in ceremony outside Metro Transit Authority Headquarters.Alfonso's assignment will be to train with two K-9 deputies. His mother said an experience like this means everything to her child."It's pretty tough seeing him at his down times and now that I could see him smile, this is his passion," she said. "I know that one day he's going to be a K-9 officer.""We are always glad to have the opportunity to make even one kid smile," Acting Transit Division Chief Commander Michael Claus said.Drying away tears from his face, Alfonso was fitted with his own vest and handed a leash, before being escorted away in an armored vehicle."I'd like to say thank you, it's been an honor," Alfonso said.