Berkowitz, who confessed to killing six people and wounding several others in New York City in the late 1970s, reached a settlement with lawyer Hugo Harmatz this week, The New York Post reported.
Harmatz had allegedly stolen the infamous killer's last will and testament, bar mitzvah photos and letters from Neysa Moskowitz, the mother of Berkowitz's last victim.
Harmatz then used the materials in a self-published book, "Dear David."
"We got 100 percent victory and justice has been served," Berkowitz's new lawyer, Mark Jay Heller, told the newspaper.
Heller said the serial killer, who is now a born-again Christian, was grateful Justice Sherry Heitler afforded him even-handed justice despite his being an admitted murderer.
Heller also said Berkowitz harbored no ill will toward Harmatz and was praying for him.