He should plead not guilty, make no statements, admissions, or confessions about the matter.
He should not show the written statement to the police, or anyone.
He should not discuss this matter with the police, the other defendants in this case, or the persecutor.
You should do what I suggested for him to do.
He should hire a lawyer, or ask the court to appoint a lawyer to represent him.
Once he has a lawyer, then and only then, he should share the statement with his lawyer.
If he's a convicted felon, there still might be trouble brewing for him.
But, under no conditions should he speak to anyone about this, except his lawyer (when he obtains one)!!!!
If he's in jail, do not discuss his case in person or over the phone.
They record everything said in jails.