Now, to why Tommy should be afraid: felony murder.
A far lesser-known offense is felony murder and its counterpart, attempted felony murder. Felony murder occurs when two or more people commit a dangerous felony together, such as an armed robbery or a burglary. During the course of that felony, a person is killed. Those involved in the commission of the felony may be charged with felony murder - even if they had no role in the killing. For example, if Alfred, Byron, and Christopher decide to hold up a local convenience store armed with semiautomatic weapons, they are committing armed robbery. Imagine that as Byron and Christopher are fleeing the store with stolen cash and Twinkies, Alfred turns around and shoots the clerk, Gustav, so that he cannot identify the robbers later. If Gustav dies, Alfred could be charged with murder, and Byron and Christopher could both face felony murder charges - despite the fact that they did not act to kill Gustav. If Gustav was seriously wounded but did not actually die, Alfred could be charged with attempted murder, while Byron and Christopher could be charged with attempted felony murder. Felony murder is often punished almost as severely as murder itself, although the death penalty is not available for a conviction of felony murder in Florida.
http://miamicriminallawyersblog.com/2009/05/floridas-felony-murder-rule.html
Let's postulate that Joe, Misty and Tommy were present and involved in committing a dangerous crime when Haleigh died and that one of the three murdered her. (That crime might have been drug trafficking, theft, burglary or worse--see below.) Thus, if Haleigh was killed or murdered as a result of the crime, all three could be charged with felony murder.
Now, one of the most serious felonies in Florida is "lewd and lascivious molestation":
Life Felony: It is a life felony if a person over the age of 18 commits Lewd and Lascivious Molestation on a child under the age of 12.
Life Felony Penalties
A first time offender charged with Lewd and Lascivious Molestation punishable as a life felony would be facing:
•A maximum sentence of life in prison, and
A minimum sentence sentence of twenty-five (25) years in prison followed by probation or community control for the remainder of the person's natural life.
http://www.richardhornsby.com/crimes/battery/index.html#Reclassified
So just molesting Haleigh would have meant a life sentence for the perpetrator. If she had been badly injured or killed in the act, and the perpetrator implicated the other two as part of the assault (e.g., giving the molester access or permission)--felony murder, again. Such an assault would mean multiple charges for the rape of a child and murder. That looks like the death penalty to me.
Now, let's think about how this scenario fits into Misty's various stories. Early on in the case, she said that she had been molested by Joe and Tommy. What if the grain of truth in this story is that there was a molestation, but it wasn't Misty; it was
Haleigh. And both Joe and Tommy were involved. If Haleigh was badly injured or died, or if one of the perpetrators decided she had to be killed to cover up the assault--well, all three of them were on the hook for murder. There would be no explaining to RC or LE why Misty didn't stop the assault or call 911.
This scenario also fits with Junior's story (seeing a man take Haleigh and seeing the "bouncing couch," which could have been either a sexual assault on Haleigh or her murder.) It fits with the need to change sheets, talk about washing bedding, and Misty's confusion about what Haleigh was wearing. It fits with the blood in the van, the van being moved, and the damage on the vehicle. It fits with the rope and cinder blocks and the need to stage the crime scene. It fits with Misty's decision not to talk to Ron (she was partying earlier and then there was dealing with what happened to Haleigh). It fits with the decision to wait until RC came home to call 911, because it needed to look like Misty just woke up. If Ron had been involved, it would have worked better as an alibi for him to get an emergency call at work, to cement the alibi.
I suppose that Joe O. could just be a crazed homicidal maniac who was thwarted in stealing a gun. But that story is, I think, the last desperate lie that Tommy and Misty are telling to cover up whatever it is that all three of them were involved in that night.