In a bombshell death row confession, Scott Peterson has at last revealed how he mercilessly strangled his pregnant wife Laci as she happily watched a Martha Stewart TV show.

Then the coldblooded monster calmly read "Playboy" in his fishing boat before dumping her body overboard, according to a blockbuster new book — previewed exclusively by The ENQUIRER.

As he munched on a turkey sandwich in a San Quentin prison visiting room, Scott made his chilling confession to friend Donna Thomas. "I could actually feel (Laci) die," he told her. "When she stopped fighting, I could feel all her weight on my arm."

Thomas’ book – "I’m Sorry I Lied to You: The Confession of Scott Peterson" – finally provides the answers all America has sought since 27-year-old Laci’s body washed up in San Francisco Bay in 2003.

The author, a lawyer, visited Scott dozens of times after he was sentenced to death. She was a passionate believer in the notorious fertilizer salesman’s innocence – until she caught him in a lie in June 2006.

Then after she confronted him, the 35-year-old killer spilled his guts, Donna told The ENQUIRER in an exclusive interview.

Surprisingly, his motive for murder wasn’t to be with mistress Amber Frey!

Pick up the new issue of The ENQUIRER for all the details!