How do I say?

A letter of good conduct can be obtained from your orgnazation hence your manager .

Thanks Mez.

I'll be working with children and it must be a letter from the police as a criminal record safety check.

Someone posted the procedure for that here recently I believe.  Use the search feature using different keywords and see what you can find.

A friend of mine is going on final exit and he had to do some running around to get this Police Clearance Certificate...
Not sure if someone can do it for you but the procedure he did is as follows :-
1. He went to his embassy in RIyadh and they issued him some sought of a letter, addressed to the local police to provide the police clearance certificate

2. With the letter he went to the Police station located in Batha ..they took the papers and asked him to come few days later..

3. After few days when he went, he was made to go here and there by concerned officials...finally a good cop ( if ever there is one) took him to the senior police official and after wait of some 2 hours gave him the signed papers..he saw them pulling his letter out of the trash can while he was waiting.. !!!