Get a blank piece of paper and tear off the edges of all four sides.   Then with a pen (not one with an eraser), write the guy's name as "johndoe" and say "John Doe, I twist you."   Then, write "ohndoej" and say "John Doe, I twist you; tell me the truth concerning xzy."   Do this until you get back to "johndoe"   Then, take a glass bottle and fill it with uncomfortably hot water.
Put Compeling or Commanding Oil on the paper, or rub the paper with calamus root and/or licorice root.   Twist the paper and stick it in the bottle.   If you used the calamus or licorice, put that in bottle as well.
You can also add black mustard seed to keep him from interfering and meddling in your life (with his lies), five finger grass to get him to do things for you (like tell the truth), poppy seed to dominate and weaken him, and black pepper to keep him out of your way.   Calamus root is used to dominate and control people, as is licorice root and bergamot (these three things are also used in Essence of Bend Over).   Licorice root also has the added benefit of changing people's minds and making them open to your suggestions and control.   As you add or use each plant, mention their properties and what effect you want them to have on your victim.
Add a new needle to prick his conscience and needle his mind.   Seal up the bottle and give it a good shake while saying "John Doe, I compel you to tell me the truth about xyz.   May you be disturbed and have no rest until you do so.   John Doe, you are compelled to tell me the truth about xyz."
Now go to a secluded area with hard surfaces.   Again, you get to rant at the bottle: "I compel you, John Doe, to tell me the truth about xyz."  Get ready to throw the bottle and say: "I break your will to deceive me!   I break your facade of lies!   I COMMAND YOU, John Doe, to tell me the TRUTH about xyz!"   Throw the bottle as hard as you can, with as much power as you can muster. Then, go home and put the whole thing out of your mind.
The only thing you need to buy for this spell is the calamus or licorice root (that is, if you can't dig some up yourself).   You can use any bottle, as long as it's glass and has a top.   Just wash it in hot soapy water, then pour a little salt in it.   Fill it with cold water, shake it nine times and let it air dry.