My Stepsons Are Thieves, Why Can't My Husband Kick Them Out?

The 2 have lived here over 3 months and now things are starting to disappear. First, my husband's gold cross and chain went missing. He asked, they denied. Just FYI, they are big pot smokers and gotta have money to buy that, right? One works, one doesn't. This morning, my USB cable was missing from my drawer. I went in the LR and asked if they knew where it was because they share my computer and it's unfortunately in our bedroom. I knew the answer, no, why would WE have it, WE don't upload much. So I told my husband, who confronted one of the men cause the other wasn't home which got him mad that I would tell his dad. I am intimidated by his sons, especially the younger 20 yr old cause he's like a linebacker and I'm 5 ft tall. Anyway, my husband's on the patio BBQng tonight and his son makes a big deal of charging out onto the patio and in a loud voice talking to him, then going back to the room. My husband comes in with the cable and asks if it's mine. I say yes, and he says his son found it beneath the computer table on the carpet. UNTRUE. I looked for the cable like a crazy woman, moved the tower,shook all the cords behind the tower, nothing. I did not miss it. What my husband doesn't know is that while he was outside, his son went in the hall, rummaged around in the closet he shares with his brother, briefly went back in our bedroom, THEN went outside to confront his dad. He had it all along, but wanted to make me look like a liar in his dad's eyes. He did a GREAT job! I apologized to keep the peace but my husband will hear from me tomorrow. He handed me the cable all coiled up and I never do that. That alone shows he had it tucked away somewhere. How do I show him what LIARS and thieves they are?