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By Melissa Wen

Alfonso Hoffman raised his right hand and swore an oath Wednesday -- to uphold the laws of the state and county and perform the duties of a K-9 deputy sheriff of the Transit Policing Division.

After being fitted with a green tactical vest and handed a leash, Alfonso climbed into an armored truck for his first patrol.

The 12-year-old kid crime-fighter, diagnosed with leukemia this year, got a chance to live his dream on Wednesday, joining a Los Angeles County Sheriff's Department K-9 patrol.

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