He opened secret communication with Achillas, sending him information, from time to time, of what took place within the walls, and of the arrangements made there for the defense of the city against him, and gave him also directions how to proceed.

He was very wary and sagacious in all these movements, feigning all the time to be on Caesar's side.

He pretended to be very zealously employed in aiding Caesar to secure more effectually the various points where attacks were to be expected, and in maturing and completing the arrangements for defense.
But, notwithstanding all his cunning, he was detected in his double dealing, and his career was suddenly brought to a close, before the great final conflict came on.

There was a barber in Caesar's household, who, for some cause or other, began to suspect Pothinus; and, having little else to do, he employed himself in watching the eunuch's movements and reporting them to Caesar.

Caesar directed the barber to continue his observations.