At least 9 dead in church shooting in SC

[cobrat]

The state’s prosecutors in Charleston should strike a deal with Dylann Roof. In exchange for not putting him on trial, he must agree not to appeal his federal sentence and he must decline to accept a federal pardon for at least 25 years.

Do the prosecutors have the power to offer terms which obligate him to not exercise his rights to appeal/accept a pardon if offered? Not sure that can be offered without it being challenged with a decent chance of success.