Many police once thought all the motivation people needed to report crime was a sense of civic duty and a few words from Officer McGruff, the cartoon bloodhound who barked "take a bite out of crime."

Not anymore. Police are increasingly turning to cash rewards and morbid crime re-enactments on television to lure John Q. Public to the phone.The police-sponsored "Crime Stoppers" genre, most familiar as 60-second spots on local TV, took a giant leap toward Hollywood last week with broadcasts of "Manhunt: A Chance to End the Nightmare."

With help from an independent film company, Seattle police investigators created two hours of televised murder, mayhem and mystery in a plea for clues to the country's worst unsolved serial murder case: the "Green River" slayings of at least 40 women in the Northwest.

The syndicated program, distributed to 137 stations nationwide, included a re-enacted murder attempt, real footage of police unearthing a victim and interviews with grieving relatives. Viewers were urged to turn in a crook - and maybe collect a $100,000 reward.

"The show was designed to push an emotional button in the viewer," said producer Beth Broday.

It apparently did. The program, broadcast Dec. 7 and repeated during the past week, drew more than 7,600 calls to a toll-free hotline.

Investigators rejoiced at the flood of fresh tips and praised the marriage of sleuthing and the media.

"It's the most effective tool in law enforcement," declared Detective Myrle L. Carner, director of Seattle's Crime Stoppers program.

The popularity of such programs reflects a "get tough on crime revival," said Art Lurigio, assistant professor of psychology at Northwestern University and co-author of a 1986 study on the programs for the U.S. Justice Department.

"People are looking to have some impact on crime, alleviate their fears, and regain some control," said Lurigio, although he cautioned "there may be some negative consequences."

Offering large cash rewards and anonymity may encourage false accusations, and the nightly re-enactments could unnecessarily increase fear of crime, Lurigio said.

Crime Stoppers began 12 years ago in Albuquerque when police and civic leaders decided they needed a new weapon to fight increasing crime. The premise: grab attention with a televised "Crime of the Week" re-enactment, then promise cash rewards and anonymity to anyone reporting any serious crime.

The concept took off. More than 600 U.S. communities now have Crime Stoppers programs, said Tim Kline, a retired Albuquerque police officer and president of Crime Stoppers International, which helps set up local programs.

Crime Stoppers tips have helped solve more than 210,000 felonies and led to the recovery of $1.3 billion in narcotics and stolen property, Kline said.

During "Manhunt," viewers were urged to report clues not only to the Green River case, but to any serious crime in the country.

Calls came in from every state. At least two people said they were the Green River killer. Several others said the killer had confessed to them.

Some calls were pranks, and many offered information too dated or general to be helpful. Investigators said it will take weeks to sort through the 3,000 tips.