CSI - NY - The Game

Episode 2: Just Desserts: Kitchen:
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Use the gas can (which you should have collected) on the
propane lighter-like object located in the back of the 
kitchen. This will allow you to collect the lighter. Use
the lighter on the cabinet door (located under the sink)
with a round lock on it. 
This will open the door, allowing you to get the antifreeze
and the apron.