The new driver.Connection interface does not have a method for killing a connection completely (as in, closing the underlying net.Conn as opposed to returning the connection to the pool).
A new interface can extend the driver.Connection interface with an Expire() method that kills the underlying connection, or an Expire() method can be added to the existing interface. There should also be an Alive() method to check if a connection is still alive (i.e. its Expire() method has not been called).