Even for longtime fans of old Hollywood Gossip, there is still so much to know about the life of Marilyn Monroe.

America’s troubled sex symbol drew a target on her own beautiful back!

Marilyn Monroe knew too many shocking secrets about too many powerful and dangerous people – and had a bad habit of writing them down in a “little red diary.”

President John F. Kennedy, his brother Robert, top mobster Sam “Momo” Giancana, Frank Sinatra’s Rat Pack, and a Hollywood who’s who all had good reason to get nervous when the dangerous dish threatened to go public – and all had good reasons for wanting her luscious lips zipped at any cost.

Hollywood insiders weren’t surprised when she turned up naked and dead. Cynically, some wondered what had taken so long!

Marilyn had inside details on the scandalous sex antics and other forbidden activities surrounding Hollywood’s elite power players — and it was an open secret among her employees, lovers, and pals that she was “making notes” about her daily life.

She’d been married to playwright Arthur Miller, who had come under investigation in the 1950s as a suspected communist. Miller refused to name names when hauled before the House Un-American Activities Committee – desperate to protect left-leaning stars who would be “blacklisted” by movie studios. But Monroe knew where the bodies were buried… in more ways than one!

She had lesbian flings with top box office stars including Joan Crawford and bedded married matinee idols as well as politicians. And, of course, she knew the most intimate secrets of her baseball legend ex-hubby Joe DiMaggio, including the real reason for their divorce.

Her revelations would wreck careers if the truth went public. So, Monroe’s diary was pure dynamite – and worth a fortune!

Some experts on the screen siren’s life and death have suggested Giancana – or even FBI Director J. Edgar Hoover – wanted Monroe’s ledger to gain political influence. They’ve suggested that shadowy power players snatched the journal after Monroe’s death or even killed her for it!

Says biographer Darwin Porter, one of Monroe’s confidantes: “Giancana had the motive to kill her – she was threatening to blow the lid off his operations,” especially in Hollywood where his gang had a lucrative loan sharking and crooked gambling operation. She also knew all about Sinatra’s association with the Mob.

Meanwhile, Hollywood private detective Milo Speriglio claims Sam Giancana ordered “a hit” on Marilyn – as a personal favor to Kennedy family patriarch Joe Kennedy!

Certainly, the Kennedy clan had the most to lose if Marilyn opened her mouth. Both JFK and Bobby Kennedy were bedding the blonde bombshell and were top officials in the U.S. government.

The “Seven Year Itch” siren told a friend she’d written “pages and pages” about her feelings for the president, how he used amphetamines and exactly what they did in bed “to avoid straining his bad back.” The actress also made notes about the time she had a telephone confrontation with JFK’s wife, first lady Jackie Kennedy, who answered the president’s private line when she called the White House.

According to the friend, Monroe said Jackie was “ice cold” and “snobbish” but seemed to know all about her husband’s affair! Incredibly, Jackie seemed to take JFK’s cheating in stride, Marilyn declared.

While JFK was said to be very careful about engaging in pillow talk with his bedmates, Monroe did manage to pick up tidbits of political gossip and inside information, the friend added. The president’s curvy mistress found most of the talk “boring” but did write down his snappy comments about other world leaders, which would have proved very embarrassing if made public.

“Marilyn told me her diary was her closest friend and constant companion,” her pal said. “She’d write in her book every day – and sometimes more than once. She’d leave it lying around her house like it was nothing.”

Another friend, Marilyn’s one-time roommate Jeanne Carmen, revealed she witnessed RFK waiting for the superstar to get dressed when he “saw a little red book on the coffee table, looked through it and seemed to get upset.”

Says Carmen: “When Marilyn came out of her room he asked, ‘What’s this?’ She said, ‘That’s my diary.’ And he said: “Get rid of it.’”

And yet another pal said the actress told him the diary was her “insurance policy.”

Investigators claim desperate Monroe tried to play her trump card when Bobby threatened to break off their affair a few weeks before she died. She told him she’d tell-all at a press conference – and back it up by producing her diary, which also noted times and places of ALL her romantic rendezvous.

The heartsick glamour girl was really only trying to keep Bobby in her arms, say insiders. But instead, she pushed him further away. Her threat put him under tremendous pressure.

As America’s Attorney General, RFK was getting law enforcement reports indicating his involvement with the buxom blonde was open knowledge in the underworld – and his president-brother was at risk of being exposed, too.

Bobby was also told he’d been photographed in comprising situations. He learned that Marilyn’s home had been bugged – by several different people – and his brother’s romps with the blonde were caught on tape!

Word is the Kennedy boys decided her “little red diary” had to be destroyed – and if she went too, they’d be fine with that. Monroe had become a dangerously broken toy.