not trust someone as far as you can throw them
not trust (someone) as far as (one) can throw (them)
To be very suspicious of someone; to not trust or believe someone. You want me to tell our plans to Jill? I don't trust Jill as far as I can throw her. The government is asking us to believe that they'll apply the new tax fairly, but I wouldn't trust them as far as I can throw them.