DUANE “DOG THE BOUNTY HUNTER” CHAPMAN marked for death by uber-sicko and now the FBI is investigating the lurid e-mails.  WARNING GRAPHIC CONTENT

Duane "Dog the Bounty Hunter" Chapman and his family have been targeted in threatening and terrifying e-mails the past few weeks which has now lead to an FBI investigation.

The source of the e-mails sent the disturbing communications over four days, threatening murder, rape, kidnapping and other horrific, unspeakable acts, RadarOnline.com reported.

On April 30, Dog received an email that read: "I'm going to murder you. I'm going to come to Hawaii and murder you and your family in cold blood. You are next on my list and are the bane of society. I will deliver you to God."

Then, on May 2, another email arrived from the creep, reading: "I'm going to murder you and your family. I'm going to slaughter your family. I'm going to cut the fat t**s off your wife while I watch your children bleed.

"I want to see you cry, like you did everyday in prison. I want you to watch as your family gets massacred right in front of you …”

A day later, on May 3, the e-mailer wrote: "Your children looked nice today. As previously stated, I have a rather nasty vendetta against you and your family.”

EXCLUSIVE DOCUMENTS: Read The Terrifying Dog The Bounty Hunter Emails