Just as a follow up -
After checking, there were eight months left on the lease. After some back and forth, my property management company has negotiated a settlement with the tenant where he pays four months rent to buy out the remainder of his lease. He will pay two months now, one month in November and forfeit his deposit, which is one month. The property appears none the worse for wear, so using the deposit seems OK. He will be released from the lease upon receipt of the November payment.