There are a few steps to correct this. But first let me explain what is going on (so you can understand the steps you need to correct)
Whenever a soldier
is arrested, the arresting agency will input a report of that arrest into the FBI Criminal Database. This data base (called the NCIC for National Crime Information Center) is available to law enforcement nationwide.
After the initial arrest, the agency that made the report has a duty to follow up and input the resolution of the case. SO, for example, if a soldier is arrested but never goes to a criminal trial, the NCIC record should reflect the arrest and that there was never a conviction.
What you describe? It sounds like there is an error in the NCIC.
The first thing that your grandson will want to do is request a copy of his military record. he can do so herehttp://www.archives.gov/veterans/military-service-records/
Make sure he requests the entire record. There is no cost and it takes a few weeks to have it sent.
Next, he can request his NCIC file. He can do so herehttp://www.fbi.gov/foia/requesting-fbi-records
This will also take several weeks to process.
Once he has his records and the FBI records, he will be able to see if the FBI records are accurate.
IF they are not accurate? Then he can write to the agency that arrested him...they are the ones responsible for corrections. I would mail them a copy of his military record and NCIC record. That would show the discrepancy. That should be enough to get them to correct
Now...it may be that the record is accurate. There should be a record of his arrest. That is not something that can be removed...if it is accurate, they are not going to change the record
But if the record is not accurate? If they claim he was convicted and he was only arrested, they can change the record to reflect the truth
Let me know if you have more questions...happy to help if I can