Sharing Conviction and PNC data with USA

Dear Sir or Madam

I wish to know the current procedure's in place for information
on the Police National Computer and any other criminal
conviction related information held by Scottish Police forces to be
shared with the United States authorities.

I also wish to know if the United States authorities ie; US Embassy
in London or the US Homeland Security have access to criminal
conviction information of individuals who travel to the US.

I would like to know how the US authorities have the ability to
check whether an individual from the UK has a criminal record.
This presumably relates to any agreements that are in place between
the US authorities and the Home Office for the sharing of such
information.

Yours faithfully,

John Anderson