MOSFET Switch - Not Turning Fully Off?
Your results are inconsistent with expected operation.
 Either you are not doing what you think you are doing or the MOSFET is damaged or your test meter is of very low "ohms per volt".

Test1: Connect test meter with -ve probe to ground and +ve probe via 1 k to 3V3.
 What is the voltage reading?

This should read 3V3 to a very close approximation.
 If it does not give or throw the meter away and get a slightly better one :-).  

Any meter that reads wrongly in that situation is a VERY poor one and useful only for eg battery testing. 

Test2:  Set meter to diode test range.
 Measure Drain -  Source.
 With Source  = +ve you should see a diode with Vf higher than a usual silicon diode.
 With +ve on Drain you should see O/C.
 With metetr connected either way G-D and G-S you should get open circuit.

Test 3 Ask Olin for advice.

Test 4: Check your circuit carefully.
 Recheck MOSFET pinouts.

Try a new FET.

Note that MOSFETS are VERY prone to ESD damage - especially gate to D or S.
 Handle with proper electrostatic precautions.



Report back.