I’d guess it’ll be hard to get a conviction after so long. If he was only a suspect back then let’s hope they have some good evidence.
Unless they saved some DNA evidence with a super chain of control, in the hopes that it would someday be useful, I can't see how a sane jury could ever convict without a confession. 54 years clouds a lot of memories, kills a lot of "witnesses", and makes moot most prosecution-oriented evidence. A half-wit defense attorney should be able to handle the job in his sleep.