Sideshow: Did Diddy order Tupac hit?

In an explosive allegation, a former Los Angeles police detective who worked on the investigation into the '96 murder of Tupac Shakur claims the rapper was gunned down at the behest of hip-hop mogul Sean "Diddy" Combs.

In excerpts cited in L.A. Weekly, Greg Kading writes in his book Murder Rap that a Southside Crips gang member named Duane "Keffe D" Davis claims he was paid $1 mil to kill Shakur and his friend, former Death Row CEO Marion "Suge" Knight, at Combs' behest. Combs "took me downstairs," Davis is quoted as saying, "and he's like, 'Man, I want to get rid of them dudes.' "

Kading says that after Shakur was killed in Las Vegas on Sept. 13, Knight paid another gang member to kill Biggie Smalls (Christopher Wallace) in retaliation. (Wallace was killed in March 1997.) Kading says Knight, who was in prison at the time, had one of his lovers, Theresa Swann, set up the hit. Combs calls Kading's claims "pure fiction." Knight has yet to comment.

In an awful confluence of events, there's yet more Tupac Shakur news: There's a Shakur sex tape. (Seems the famous aren't allowed to rest in peace.) TMZ claims the five-minute vid, shot in '91, shows Shakur receiving oral sex while rapping and dancing at a party. Its owner, not named by TMZ, reportedly is gearing up to release the vid for public consumption.

Jenna Fischer, 37, of The Office fame and her husband, Lee Kirk, welcomed their first child, a boy named Weston Lee, on Sept. 24, USA Today has revealed. Fischer's pregnancy was featured on her show: Her character Pam has been pregnant with TV hub Jim Halpert (John Krasinski). So, will the baby be added to The Office cast?

The Combover is a grandpa again: Donald Trump Jr. and wife Vanessa welcomed grandson Tristan Milos on Sunday, Trump Jr. announced by Twitter. "I am delighted," The Donald (Sr.) says. Tristan joins Donnie John III, 2½, and Kai Madison, 4.

Singer John Rich, 37, of The Big & Rich and wife Joan, 41, have a new baby son. Colt Daniel joins 20-month-old Cash.

Two-time Dancing With the Stars winner Julianne Hough will make a rare (and so delightful) guest appearance on DWTS on Oct. 11 to promote her dance-heavy (and really quite fun) new flick, a remake of Footloose. Hough tells USA Today she'll dance on the show with her Footloose costar, pro dancer Kenny Wormald, who has some smokin' moves in the film.

Sports news site SB Nation (www.sbnation.com) claims (in an Exclusive!) that a most football-womanly diva will perform the halftime show at Super Bowl XLVI on Feb. 5: Madonna.

Rumors the Spiritual Mom was to grace the NFL's version of the Senior Prom have preceded every Super Bowl for the last million years. What's new this time?

The NFL has refused to comment.

Martha Stewart, the ex-con we so love for her extraordinary domestic skills, was always better at basting the turkey than raising a human child. So claims Martha's 46-year-old daughter, Alexis Stewart, in a scorching Mommie Dearest-type portrait of her ma in a new memoir, Whateverland: Learning to Live Here. Alexis' memories aren't exactly warm, as excerpts published in London's Daily Mail reveal.

"Martha does everything better! You can't win!" Alexis writes. "If I didn't do something perfectly, I had to do it again. . . . I grew up with a glue gun pointed at my head." Martha, her daughter says, wasn't very people-friendly: On Halloween, she writes, "there were no costumes. There was no anything. We turned off all the lights and pretended we weren't home."

And the sin of all sins, especially given Martha's metier, "there was never anything to eat at my house."

CNN's Andersoon Cooper says he is mortified that an unnamed teen has been severely injured while attempting a stunt indirectly suggested by producers of ACoop's new show, Anderson. Gawker reports that the show's staff encouraged the lad to video some of his stunts and other "crazy stuff you do" as part of an episode on "the teenage mind."

The boy filmed himself doing a skateboarding stunt, fell, and hit his head. He is in a coma.

"I was very saddened to hear the news of this accident," Cooper says in a statement, "and want to express my deepest concerns for the teenager who was injured. I take this situation seriously."

A new Michael Jackson CD is due Nov. 21. Immortal will feature tunes reshaped for Cirque du Soleil's "Michael Jackson The Immortal World Tour," which launched Sunday in Montreal. 

Aubrey O'Day, 27, who starred in Sean "Diddy" Combs' MTV reality show, Making the Band, will be one of the contestants on next season's Celebrity Apprentice, Life & Style Weekly says. . . . Target will feature a line of fashions by one of first lady Michelle Obama's fave designers, Jason Wu, the chain store has announced. . . . Former Hercules star Kevin Sorbo, 53, tells Neurology Now (a sexy periodical) that he suffered several strokes in the late '90s while doing stunts. He's publicizing his memoir, True Strength: My Journey From Hercules to Mere Mortal and How Nearly Dying Saved My Life.

Halle Berry, who is in Spain shooting Cloud Atlas, has broken her right foot while on a walking trip in Majorca, studio Warner Bros. says. Anonymous Source tells People mag the incident was quite colorful: Seems the Swordfish star stumbled over a rock chasing after 3½-year-old daughter Nahla, who in turn was chasing after a goat across a field.