Dominick Dunne has made a career writing about celebrity murders. Now he has his own true-crime movie franchise on the USA network, which debuts tonight with “Dominick Dunne Presents: Murder in Greenwich” (7 p.m.), starring Christopher Meloni.

“Greenwich” is based on the true-crime book by former Los Angeles Detective Mark Fuhrman (Meloni), who became well known ” even notorious ” for his part in the O.J. Simpson murder trial. After penning his best-selling book about the O.J. case, Fuhrman turned his attentions to the 1975 murder of Connecticut teen Martha Moxley. The case had earned attention when Kennedy family nephews Tommy and Michael Skakel became suspects, but it remained unsolved for more than a quarter century.

Meloni, who stars in NBC’s “Law & Order: SVU,” does a good job as the embittered Fuhrman. Convinced that most people despise or distrust him, Fuhrman conducts most conversations with a pre-emptive rudeness. He gets even pricklier when he begins to snoop around the Greenwich country clubs and commuter bars.

Had “Murder” concentrated on Fuhrman’s detective work and his awkward interaction with Greenwich’s insular police force and snooty natives, it might have become a fine film. Instead, the movie relies on narration by the dead Martha Moxley (Maggie Grace) to relate most of the story. Since many of the film’s key revelations rely on the testimony of a dead girl, we never really learn how Fuhrman ferreted out the facts. “Murder” quickly becomes two separate movies. Meloni stars in a hard-boiled gumshoe drama, while Grace narrates a gauzy fantasy that seems inspired by “American Beauty” and “The Ice Storm.” As you can imagine, these divergent styles never quite mesh.

• “Now with Bill Moyers” (8 p.m., PBS) looks at loopholes in U.S. gun laws that have allowed terrorist groups to buy weapons and ammunition at American gun stores and gun shows. One suspect transported more than 800 assault rifles to shadowy Venezuelan gun merchants without raising an eyebrow. He was able to buy 100 Mak-90s at a time.

“Now” also questions the influence of the National Rifle Assn. on U.S. policy, and particularly on Atty. Gen. John Ashcroft, who last autumn limited the FBI’s ability to use gun records to investigate gun purchases by suspected terrorists.

• “Pumping Iron: 25th Anniversary Special” (7 p.m., Cinemax) takes an affectionate look back at the 1977 documentary that launched the movie career of Arnold Schwarzenegger and changed popular attitudes towards body-building and physical fitness. As Sylvester Stallone relates in a short introductory film, in the early 1970s, one would never have suspected that eventually “you would go to the gym to meet women.”

Tonight’s other highlights

• Scheduled on “48 Hours Investigates” (7 p.m., CBS): a 4-year-old accuses his father of being a killer.
• A traitor emerges in the ranks on “Firefly” (7 p.m., Fox).
• Jim Carrey and Cameron Diaz star in the 1994 comedy “The Mask” (7 p.m., UPN).
• A disgruntled airline employee sabotages the first fully automated jetliner in the 2002 thriller “Cabin Pressure” (7 p.m., PAX).
• Avril Lavigne performs on “Sabrina, the Teenage Witch” (7:30 p.m., WB).
• Mike spends Thanksgiving trying to identify the man who died in his cab on “Hack” (8 p.m., CBS).
• A recently released con threatens the witness who put him away on “Robbery Homicide Division” (9 p.m., CBS).
• A predator targets the comatose on “Law & Order: Special Victims Unit” (9 p.m., NBC).
• Scheduled on “20/20” (9 p.m., ABC): Barbara Walters interviews former Vice President Al and Tipper Gore.