He had been in the habit of sending out armed parties on slave- hunting forays among the helpless tribes to the north-east, and carrying down the kidnapped victims in chains to Quillimane, where they were sold by his brother-in-law Cruz Coimbra, and shipped as "Free emigrants" to the French island of Bourbon.

So long as his robberies and murders were restricted to the natives at a distance, the authorities did not interfere; but his men, trained to deeds of violence and bloodshed in their slave forays, naturally began to practise on the people nearer at hand, though belonging to the Portuguese, and even in the village of Senna, under the guns of the fort.

A gentleman of the highest standing told us that, while at dinner with his family, it was no uncommon event for a slave to rush into the room pursued by one of Mariano's men with spear in hand to murder him.
The atrocities of this villain, aptly termed by the late governor of Quillimane a "notorious robber and murderer," became at length intolerable.

All the Portuguese spoke of him as a rare monster of inhumanity.

It is unaccountable why half-castes, such as he, are so much more cruel than the Portuguese, but such is undoubtedly the case.
It was asserted that one of his favourite modes of creating an impression in the country, and making his name dreaded, was to spear his captives with his own hands.