He is popularly known as former Director of Vigilance & Anti-Corruption Bureau (VACB), Government of Kerala,[1] and a recipient of the Police Medal for Meritorious Service as well as the Newsmaker of the Year Award of Malayala Manorama.

He held the post for almost five years before moving to the Motor Vehicles Department of the Government of Kerala in 2003 as the Joint Transport Commissioner.

[22] Jacob Thomas has been involved with a number of non-governmental organizations such as Top Centre, Darshan, and ExcelKerala, the last one a platform for open exchange of information on governance.

[30] The biggest allegations against Jacob Thomas was that he holds undisclosed land in multiple states including 50 acres in Sethur village in Rajapalayam taluk of Virudhunagar in Tamil Nadu.

[6] In January 2017, a writ petition was filed against him at the Muvattupuzha Vigilance Court alleging corrupt practices while he was heading the Kerala Transport Development Finance Corporation.

[31] Earlier, he had alleged that his actions against political leaders such as R. Balakrishna Pillai, C. Divakaran and K. Babu were the reasons for removing him from the post of the vigilance director in his first stint.

[33] At the time of retirement, he was facing a government-level probe for penning an autobiography without obtaining prior sanction had found him of having committed serious breach of discipline and criminal misconduct that should earn him major disciplinary actions.

[36] Thomas joined Bharatiya Janata Party in 2021 and was nominated to fight 2021 Kerala Legislative Assembly election from Irinjalakuda constituency.