what are possible outcomes of a 2nd degree murder case with no physical evidence and with witnesses who refuse to comply with prosecution?

At the time of arrest their were eye witness accounts that was 3 years ago. Since then there has no physical evidence, no weapon and charge has gone from first degree to second degree murder. The witnesses are not complying with prosecution or willing to testify. There was no pre trial so the PD was not able to cross examine. What are possible outcomes? Can testimonies from crime scene be used in court if the witnesses dont show?