LOWER ARKANSAS VALLEY — On a hot June night in La Junta, a group of Otero County sheriff’s deputies and local police officers stormed the one-bedroom apartment of a suspected drug dealer on the west end of town, hoping to find a bounty of heroin. “Get on your stomach! … Don’t move!” law enforcement yelled before leading out five people in handcuffs. After about two hours of searching through books, boxes, furniture and shelves, they had found little: a small rock of suspected black-tar heroin, a bit of methamphetamine residue and a mass of paraphernalia that included baggies, apparent pipes and a small scale. “We better find more than that,” a deputy said as he rifled through a safe by hand. But the raid became another frustrating reminder that it’s difficult for small-town officers to keep up with drug distributors as heroin spreads across the Lower Arkansas Valley, in communities from Fowler east of Pueblo to Holly along the Colorado-Kansas state line.