He proved that the Thug crimes were committed by a numerous and highly organized fraternity operating in all parts of India.

In consequence of his reports, Mr.F.C.Smith, Agent to the Governor-General in the Sagar and Nerbudda Territories, was invested, in the year 1829, with special powers, and the author, then Major Sleeman, was employed, in addition to his district duties, as Mr, Smith's coadjutor and assistant.

In 1835 the author was relieved from district work, and appointed General Superintendent of the operations for the suppression of the Thug gangs.

He went on leave to the hills in 1836, and on resuming duty in February, 1839, was appointed Commissioner for the suppression of Thuggee and Dacoity, which office he continued to hold in addition to his other appointments.
Between 1826 and 1835, 1,562 prisoners were tried for the crime of Thuggee, of whom 1,404 were either hanged or transported for life.
Some individuals are said to have confessed to over 200 murders, and one confessed to 719.

The Thug approvers, whose lives were spared, were detained in a special prison at Jubbulpore, where the remnant of them, with their families, were kept under surveillance.