Security tag with tack position feedback

A method for verifying a detachment of a security tag from an article, comprising:

• using a voltage induced in an internal circuit of the security tag by a magnetic field generated by a detaching unit to power a controller of the security tag;
• receiving, by the security tag, a first signal sent from the detaching unit;
• selectively supplying power to an electro-mechanical lock mechanism of the security tag for a certain amount of time to cause a pin to be released from a lock, in response to the first signal;
• detecting, by the electro-mechanical lock mechanism, whether or not the pin was released;
• and
• communicating, from the security tag to the detaching unit, a second signal in response to the detection, the second signal indicating whether or not the pin was released;
• wherein the voltage is no longer induced in the internal circuit by the detaching unit when the second signal indicates that the pin was released;
• wherein the detaching unit is distinct from the security tag;
• and
• wherein the detection triggers the communication of the second signal.