Tinseltown is abuzzing with twitters that Oksana Grigorieva’s younger sister, Natalie, is responsible for leaking a series of damning audio tapes, featuring an enraged Mel Gibson ranting, raving, and hurling death threats at the mother of his infant daughter with the same ease that parishoners exchange pleasantries on a Sunday morning, to the gossip aficionados at RadarOnline.com.

If a nagging feeling in the pit of you stomach told you that there must be some law against recording conversations, your gut was on to something.

Police in Los Angeles are investigating suspected battered mom Grigorieva for allegedly extorting her volatile former flame, Oscar-winning actor Mel Gibson. However, in Hollywood circles, it hasn’t taken gawkers long to turn their suspicions in on Natalie.

“I suspect that if the authorities look at the sister, they’ll find a wire transfer or a check to her from the website,” a well-placed informant told The Hollywood Reporter Friday. “She and Oksana are very close.”

Another source with knowledge of the Grigorieva-Gibson custody battle over Baby Lucia is also taking. This snoop claims that Grigorieva’s sister was involved in shopping the audio tapes to various media outlets before they finally appeared on RadarOnline two weeks ago.

“All the tabloids said no to the deal because they were asked to purchase the audio tapes before hearing them..”

Even if it was Natalie, not Oksana, who sold the Mel Mel-tdown Tapes to RadarOnline, the oldest of The Grigorieva Sisters may still face possible extortion or contempt charges, based on a text and emails that she sent Gibson. In one questionable text message, Grigorieva wrote Gibson that the reason she recorded him was because “you broke your agreement with me.”

Mel’s text messages are equally damning to the assault case Los Angeles cops are building against him steaming from the reported Jan. 6 attack on Oksana. He writes, among other things: “Oksana, I wasn’t safe for you last night. I spent two hours with a therapist today and have regained some perspective. What I’m telling you know if I am safe & would like to come by and make amends to you, sascha and Lucia.” She responds: “I have two broken front teeth and a concussion. I can not c u today, I’m hurting.”

RadarOnline has refused to confirm how they obtain the tapes.