Well, see, this is one of the pro-innocence arguments: That if they really were involved, he would openly say so. The vagueness may be because his conscience doesn't really want to fully blame 2 innocents. From the guilty perspective, it is very hard to explain. Say you committed a murder with me, and now you're caught and sentenced, and I am suspected but keep swearing I was never there. Wouldn't you want to set the record straight?
Conscience? Oh, sorry, I don't believe it has one bit to do with conscience. In the innocence scenario, he did it with full malice, and it is also suggested that he did other evil things like rape her after she was dead. Someone rapes someone after they stab to death, and we are supposed to believe that now suddenly he cares about two innocent people he has nothing to do with.
In the guilt scenario 1 of some kind of assault, he is also malicious, although maybe a step below innocent scenario because it might have been a group dynamic and things got "carried away", understatement of the year. In the guilt scenario 2 of prank gone wrong and perhaps accidental death, he is still pretty malicious to then go ahead and kill her off and then leave her to die.
I don't think he is doing it out of any concern for Amanda and RS well-being or any conscience.
I see it as the opposite:
I am looking at it from the time perspective of the beginning days when he got arrested, not now when it is clearly better for him to stay silent.
- in the guilty scenario, it is very clear to me why he would not fully reveal their involvement, as that would more fully reveal his own involvement and also make him susceptible to having them reveal his involvement.
- in the innocent scenario, I don't understand why he would
not blame them for the murder itself? He was trying to deny actually killing Meredith, Amanda and RS were being suspected and arrested for that - thus the natural and most logical thing would be to say that they committed the murder itself, and he had some peripheral role not involved with the killing itself. Yet why this hesitation? I do not believe it's because of some kind of conscience and he doesn't want to hurt two innocent people.