First, seeing the abbreviation I, too, thought of the capital region public transport system YTV, but then found out the other meaning. Would that fit your context? A police officer who was having a day off, compensating work done on overtime?

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Note added at 21 mins (2009-07-03 20:02:35 GMT)
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Eek, a spelling mistake! Of course, should be ylityövapaa.

meaning general judicial power; general authority to render decisions;
tuomioistuimen yleistoimivalta = universal jurisdiction

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Note added at 58 mins (2009-07-03 20:39:07 GMT)
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Police officers interrogating immigrants are empowered to return them to their country of origin if they do not meet immigration requirements.

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Note added at 1 hr (2009-07-03 20:49:27 GMT)
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yleistoimivaltainen is used to refer to bodies (yleistoimivaltainen elin) it might by extension be used to refer to the powers of police officers.

The Finnish law requires that in every organization there have to be 'yhteistoimintaelin' (employer-employees cooperation body). The members of this 'yt-elin' are 'yt-valtuutettuja' (representatives of either the employer or the employees).

Yt-valtuutettu is allowed to be present in work-related interrogations (I have myself once been in that role in one interrogation).

If the interrogation is somehow work-related, it is possible that 'ytv' is an abbreviation of 'yt-valtuutettu'.