Jacob was born to parents who were both schoolteachers at Thumpamon in Pathanamthitta District, Kerala. He had his school education at St. Goretti's School, Nalanchira, Trivandrum and at Mar Gregorios School, Thumpamon.
He studied chemistry at St. Xavier's College, Trivandrum and undertook postgraduate studies at Mar Ivanios College. He studied at Master's Degree level in Engish, History, Politics and Sociology. He undertook research for a PhD in English Literature on Historical Novels of Indo-Anglian Literature.
He started his career as a subeditor of a newspaper in Kerala before working at the Indian Overseas Bank and then as a lecturer in English at Mar Ivanios College. He was recruited to the Indian Police Service (IPS) in 1982.
After his probation Jacob was posted as Superintendent of Police, Kottayam and subsequently at Kannur. He also worked as the Commissioner of Police, Kochi City in 1990. He was the principal of Police Training College, Trivandrum during 1992-1995. On promotion he was posted as Deputy Inspector General of Police (DIG), Northern Range (Kerala) and subsequently as DIG, Armed Police Battalion.
He was the Director of Kerala Women's Commission taking over his assignment as Secretary, Institute of Management in Government in January 1999. In May 2000 he was posted as Joint Director of Kerala Police Academy. He was promoted as IGP and posted Inspector General of Police (Training), Kerala State and Ex-Officio Joint Director Kerala Police Academy in 2001. In 2006 he was promoted to the Director of Kerala Police Academy. Jacob is also involved in teaching many different groups of students in the Civil Service and wider public. He gives talks based on the Bible through the programme Njanavachassukal on Shalom TV India.
He was awarded the President's Scout Award in 1972. He won Best Probationer Award (Co-curricular activities) and L.B. Sewa Cup from IPS Academy, Hyderabad in 1983. He was honoured as the most outstanding Young Person of Kerala by the Junior Chamber, Jaycees in 1989 and as most outstanding Young Person of India by the Indian Junior Chamber Jaycees in 1990.
He is married to Dr Elizabeth John, a Reader in the Collegiate Education Department. The couple have three daughters.