One incarnation of Pavo, who had the appearance of a bald man, was pursuing a criminal known as the Monk. However, the Monk shot him with Pavo's own baton. The Monk then stole Pavo's perception-altering ring in order to impersonate him.
The Monk thought that he had killed Pavo, but with the help of the Second Doctor and Jamie McCrimmon, he was able to regenerate. Pavo's new incarnation was a woman, who assumed the alias of "Commander Melanie Flail".
Pavo intended to also arrest the Doctor, but eventually, after the Doctor helped her defeat the Monk and a Seeth invasion, she decided to let him go this time, after wiping the Doctor, Jamie and Victoria's memories of the event. (AUDIO: The Black Hole)