I would think that the prosecution would want his version of events if he changed his plea to guilty of murder. Though as the life sentence is mandatory and for a fixed term of 15 yrs there is nothing legally for him to gain by doing that.
He is more likely to plead guilty to manslaughter but I think the prosecution would need him to convince them of his version of events for them to agree to not continue to prosecute on the murder charges.
I wonder if this possible new improved version of events would be half as inventive as the old "innocent" version (with holes).
Thanks alioop for your reply here. I too, have been wondering about this.