I have been doing a lot of combined word searches on Google, too, using "Pasco, WA" with things like "halal", "mosque", "Pakistan", "Pakistani", "Islam", ""Urdu", you name it. Trying to track this 31 year old buzzard down.
First name "Navin" (or something similar) from an unconfirmed KING 5 source. Apparently has a criminal record.
Good Luck.
The islamic center also has a weekend school:
I'm not finding any halal markets or islamic business other than a perfume and incense store. You would thing there would be more with an islamic community large enough to support a center.