A mystery in Florida involves a couple who appeared to be madly in love, and a gruesome discovery made on the beach.

The Florida couple Kelly Moriarty and Pat Carter went missing in Plant City, Florida on December 16, 2011, and now police are wondering if the events that happened the day before had anything to do with their disappearance.

Pat Carter and Kelly Moriarty had been dating for two years. They met after Pat's husband, Ed, a former Hillsbourough County sheriff's deputy, passed away.

The relationship came as a surprise to Pat's family, but they were supportive.

Pat and Kelly planned to spend the holidays together for the first time. The last time Kelly's family spoke to her was Thanksgiving that year. Christmas came and went, but there was still no word from Kelly.

Desperate for answers, Kelly's parents try to reach out to her partner Pat -- but they didn't know anything about her, not even her last name.

At this point, the only way Kelly's parents can get a hold of their daughter is by her cellphone. Now late January, things go from bad to worse when a voice answers Kelly's phone. It's automated -- the phone had been disconnected.

Kelly's apartment manager tells the family she is more than three weeks late on her January rent. Kelly's family hasn't heard from her since Thanksgiving.

"I thought something was wrong and he advised me to come down and fill out a missing persons report with detectives at the Bradenton Police Department," said Brenden Moriarty.

Then with a police escort in tow, Brenden enters his sister's apartment.

Once inside, it's clear nothing has been touched for a long time.

The next day, Bradenton Police detectives locate Pat Carter's home address in Plant City. And when they knock on the door to their shock and surprise, someone answers: It's Pat's daughter, Stacy Muralt. It's the first Kelly's family has heard of her.

Stacy, her husband, Anthony, and their daughter have been temporarily living at her mother's house since losing their home to foreclosure.

And when police ask Pat's daughter when she last saw her mother, Muralt tells police the last time she's seen her mother was between 10 p.m. and midnight on December 16. And according to Muralt, on the night the couple left, they couple had been fighting all night.

In fact, as court records would soon reveal, behind closed doors Pat and Kelly may have been anything but a happy couple.

Kelly Moriarty, 38, and her girlfriend, 61-year-old Pat Carter go missing. Now police wonder if it was a lovers' squabble turned deadly.

Just months before the women went missing, Pat filed a restraining order against Kelly after they got into a fight that involved a gun. Kelly also filed a counter-claim. Both were dismissed by the judge for lack of evidence.

Then detectives get a break in the case when Kelly's car was found. The black Cadillac had been abandoned alongside the road. It was a cherished gift to Kelly from Pat. And cops know exactly when the car was left there thanks to a parking ticket left on the windshield.

The Cadillac had been towed to an impound lot where it sat for over a month before the tags were run and linked the car to Kelly.

Once the car was processed, Detective Tom Dirks recalls an earlier conversation he had with the St. Petersburg Police around the holidays about a severed leg they had discovered washed up on one of their beaches two days after Christmas.

While cops wait for DNA results, a timeline for their investigation begins to emerge.

December 16: The couple is seen for the last time.

December 20: Kelly's car is discovered abandoned.

December 27: A severed leg washes up on a nearby beach.

Then on March 23, the day the DNA results come in: the remains were identified as Kelly Moriarty.

Pat Carter is still listed as a missing endangered person and the investigation remains open.

And with Kelly found murdered, she's no longer a viable suspect in the disappearance of Pat. So investigators turn their attention back to the last known people to see Kelly and Pat alive: Anthony and Stacy Muralt -- Pat's own daughter. Authorities served a search warrant at Pat Carter's home.

Among evidence claimed, an eviction notice filed with Hillsborough court. It appears Pat wanted Stacy and Anthony out.

On December 15, a judge ordered Stacy and Anthony Muralt to leave Pat's home. And on December 16, just 24 hours after that court order, the women were never seen again.

According to reports, there's bank surveillance video that allegedly shows Stacy withdrawing things out of her mother's safe-deposit box just three days after she went missing.

And, the families claim that Stacy's husband Anthony allegedly sold off Pat's jewelry and guns soon after her disappearance.

The Hillsborough Sheriff's Department told Crime Watch Daily the stance is not to discuss details in reference to the evidence that was collected.

Crime Watch Daily went straight to the source to give Stacy Muralt a chance to tell her side of the story, but we were unable to contact her.

But the Muralts will have to answer to the Hillsborough Sheriff's Department as long as, they remain persons of interest.

After five long years and no arrests, the families are understandably frustrated. The Moriarty and Carter families are united in their hope that one day this case will be solved.

Investigators are asking for the public's help to crack this case.

If you saw Kelly and Pat in the days after the were reported missing, or if you have any information you think might help this case, call the Crime Stoppers of Tampa Bay hotline at (800) 873-TIPS. Callers may remain anonymous.