It's one of the longest-standing still-active missing children's cases, but the investigation into the disappearance on young British girl Madeleine McCann has taken a surprising new turn as reports surface that her parents are now the victims of vile death threats.

According to NBC News, an 80-page dossier has been submitted to London police which details graphic tweets and Facebook posts calling for violence against McCann's parents, Kate and Gerry, with some even saying the two deserved to die.

Some of the messages, which are being described as "venomous," include calls for the young girl's parents to be tortured and killed, with at least two people saying they hoped they "burned in hell" and "I hope that the McCanns are living in total misery." Another even described a way for the two to die, saying "I want to see them smashed up in the back of a bus or trampled by horses."

One woman, who has not been named but was identified by her Twitter handle of @Sweepyface, was confronted by Sky News about the abuse she has hurtled towards the McCanns, but simply said she is allowed to speak her mind freely-and isn't concerned that the Crown Prosecution Service could prosecute her.

"I'm entitled to do what I want," she said calmly before getting into her car and driving away.

Then three-year-old Madeleine vanished from her hotel room in Portugal in 2007 while her parents dined nearby with friends. Her parents were initially named as suspects in her disappearance but were officially cleared of suspicion in July 2008. After they were cleared of the charges, they successfully sued several news organizations over their coverage of the case-winning front-page apologies and a total of $891,000 in damages from Britain's Daily Express, Sunday Express, Daily Star and Star on Sunday.

The investigation to find Madeleine continues.

Tags: madeleine mccann