Sal Melfa and his staff provided the cuts for free, but to one fashion critic they were priceless. As 16 cops and one police dispatcher left Sal's Exclusive Barbers in Ramsey, N.J., 4-year-old John Hennessy patted each of their shiny bald heads. "It's great!" he shouted. "They all look like me."

Exactly the point. To show support for John, who lost his hair to chemotherapy for leukemia, more than half of the Ramsey Police Department's 31 members sacrificed their locks on May 10. "Anything that makes him feel better and less self-conscious, we'll do," says Det. Sgt. Francis Alcaro, 40, who plans to stay shorn until John's blond curls grow back.

John's dad, Sgt. Robert Hennessy, got misty about his colleagues' act of kindness. "I expected only a handful of guys to show up," says Robert, 34, who has patrolled this town 15 miles west of New York City for 15 years. "It's overwhelming."

So is his son's spirit. John was 7 months old when he underwent his first tough medical procedure—an operation to allow the bones in his skull to grow properly. Last Nov. 7, suffering from listlessness and nosebleeds, he was diagnosed with leukemia. "He was in preschool on a Tuesday and in the hospital on Wednesday," says his mother, Christine, 31. Robert's coworkers donated their sick leave so that he could take time off to care for his son. After a month of chemo John's cancer went into remission, but he must continue treatments several times a week for 2½ years. The drugs leave him with excruciating headaches and an immune system so weak that he can't attend school or play with other kids.

But John is all smiles when he encounters the Baldies, as Ramsey residents call the chrome-dome cops. "Some of us look better than others," says Alcaro, "but there hasn't been one negative comment, even from people we arrest."