In 1973 he graduated from the Department of Urban Planning of the same faculty having earned another doctorate in technical sciences (Doktor der Ingenieurwissenschaften) as an architect-planner.

Hakhnazarian started his research activities in 1968, when he embarked on measuring St. Thaddeus Monastery in Artaz District (at present: Maku in West Azerbaijan province, Iran).

In the 1970s, Hakhnazarian made six research trips to Western Armenia (at present: Eastern Turkey), each lasting for almost two months.

In 1983 he started teaching in the Faculty of Urban Planning at Aachen University, Germany, his lecturer's career lasting for many years.

Hakhnazarian died in Aachen, part of his ashes being buried there and the rest in the cemetery of Artashavan Village, Aragatzotn Region, Armenia.