In reply to Postmanpat:
He would have been further arrested for the knife at some point. At any time up to arrest the Policeman could have used his discretion in how to deal with the knife as I've outlined earlier.
However once arrested the process would go something like this;
Subject arrested and necessity of arrest explained, any comments made recorded under caution.
Taken to custody and the reason and necessity of arrest given to the custody Sgt.
The knife booked in to property and becomes an exhibit.
The Sgt (who has no part in the investigation) makes a decision whether or not to authorise the detention.
If the subject requires legal representation, the investigating officer gives the circumstances of the offence to the solicitor.
The solicitor then meets with the subject in private for legal advice.
Subject interviewed in a recorded interview.
Depending on the interview there are several options.
-Guilty plea
-Release no further action (not in public interest to pursue prosecution)
-Caution for first offence
-Charge and bail to court (for more serious offence)
Not guilty plea
-Release 47/3 bail for further investigation, to return to custody at a later date.
-compile case file for advice
-seek advise from evidence review officer (ERO)
If ERO agrees send file to CPS for advice
Depending on advice from CPS-
-Release no further action (not in public interest to pursue prosecution)
-Charge and bail to court
-Charge and remand to court (serious cases)
The investigating officer will then prepare the file for court.
Given the above, 'words of advice' would be a much simpler route to go down, but that would very much depend on the individual at the time of the incident.