There is no evidence proving Shelia did not kill herself. Multiple gunshot suicides have been recorded many times
http://en.wikipedia.org/wiki/Multiple_gunshot_suicide
I could not disagree more with your summing up of the trial. Julie's word against Jeremy's, a contaminated forensic exhibit. much new evidence has come to light since the trial and even back then it was 10-2 despite all the controversy hardy a 'slam dunk'
This site recounts the evidence thousands of times including many posts from myself listing same.
I can understand being a newbie but a newbie should not come to conclusions without doing some research and the most basic research of all is to research the evidence that convicted the defendant.
Relevant facts:
A) Sheila was shot with the moderator attached to the gun. The fatal shot was a contact wound. The location of the fatal shot and it being a contact wound means that drawback would have resulted. Drawback means blood is drawn several inches into the weapon. The blood sprays into the weapon. The moderator had her blood on the first 8 baffles. The lab scraped all visible blood from these baffles. The defense expert still managed to find microscopic traces on the first 8 baffles. In contrast there was no blood in the barrel of the rifle. had she been shot with the rifle sans moderator then her blood would have been in the rifle not inside the moderator.
B) If Sheila loaded the rifle she would have had elevated lead deposits on her hand and in fact there would have been visible black marks on her hands
C) If Sheila fired the rifle she would have had GSR on her hands and clothing. In order to kill herself she would have to have hugged the rifle and her gown would have had GSR deposited on it. Her gown and hands were negative for GSR though she didn't even have a single particle though.
D) If Sheila had shot June and Neville then she would have had high velocity impact blood spatter from these victims on her clothing. The shooter was close enough that the backspatter would have gotten on the shooter.
E) If Sheila had beaten Neville then she would have had medium velocity impact spatter on her clothing. During the beating from the rifle his blood got all over the weapon and would have gotten on the killer as well.
F) Since the weapon was covered in blood the killer's fingerprints would have been found in such blood unless the killer was wearing gloves. There were no gloves at the scene that Sheila could have worn and no reason for her to wear gloves if she planned to commit murder suicide. People wear gloves when they hope to avoid liability.
G) After the murders the moderator was removed from the rifle and put away in the downstairs closet. Quite obviously Sheila could not have done this after she was dead.
H) After the murders the bible was placed in a pool of blood that formed after Sheila's death and while the blood was still wet the bible was closed then reopened. The closing of the bible resulted in a mirror image on 2 adjacent pages. The blood did not flow around the bible the bible was placed in the blood pool. Quite obviously Sheila could not have done such after she was dead.
I) Jeremy claims that he took a box of ammo that was full or near full from the closet and dumped it out in the kitchen. A full box contained 50 rounds so that is the maximum. 25 rounds were used during the murders. There thus should have been no more than 25 rounds remaining. There were 30 rounds remaining. This proves Jeremy staged these bullets after the murders because there is no way the killer would have used 20 bullets form this supply and decided to go to the closet to get 5 additional rounds instead of continuing to use the same supply.
J) Sheila would have damaged her nails while beating Nevill with the rifle and would have cut her hand when the stock of the rifle broke. Only if the killer was wearing gloves would the stock cracking not result in cutting or at least scratching the hand of the killer that was on the stock. It broke exactly where one of the killer's hands would have been while using it to bludgeon Neville. This is likely what tore off Jeremy's glove which he told julie had happened.
The evidence shows that Sheila didn't load the weapon, didn't fire the weapon, wasn't near her mother or father when they were shot, wasn't near her father when he was beaten, and can't have shot herself. Someone else killed everyone then afterwards removed the moderator, put it int he closet and while her blood was sitll wet placed the bible in pool of her blood.
There is no question of Jeremy's guilt to anyone who actually is aware of the facts and evidence and is objective enough to face it instead of irrationally ignoring it.