Deynes then went to study to the University of Puerto Rico at Mayagüez where he received a Bachelor's degree in Agricultural Sciences in 1955.
Deynes continued studying at the Interamerican University of Puerto Rico, and received his Master's degree in Economy and Education in 1970.
Finally, he received his Juris doctor from the Interamerican University of Puerto Rico School of Law.
He chaired the finance committee of that legislative body, as well as the Special Permanent Commission on the Retirement Systems of the Senate.
He contributed articles on various topics to the newspaper "El Mundo" Deynes began his political career in 1972 when he was elected as senator for the District of Mayagüez.