He graduated from the Premonstratensian High School in Szombathely, run by the Premonstratensian Canons of Csornai, and then applied for admission to the abbey’s novitiate, where he was given the religious name László. He entered the order on August 15, 1935, took his solemn vows on August 15, 1940, and was ordained a priest on August 20, 1940.

He began his advanced theological studies at the Theological College of the Csornai Abbey, then continued at the Gregorian University in Rome, where he earned a doctorate in theology in 1942. Upon his return, he served as the abbey’s novice master and taught moral theology, among other subjects.

In July 1950, before the dissolution of the religious orders, after being warned that their monastery would be closed, he left Hungary with six companions and fled to Austria. From there, they eventually made their way to the United States. They were welcomed by the Premonstratensian Abbey in De Pere, Wisconsin, where they served in pastoral and teaching roles.

In America, he held several positions: he was a foreign language teacher, an instructor, the rector of a preparatory college, the superior of the monastery in Orange, and a member of the board of trustees of the Mindszenty Foundation in St. Louis. In 1957, at the invitation of Cardinal James McIntyre, he began teaching at Mater Dei High School.

In 1961, as administrator of his community, he used their savings to establish, together with his fellow refugees, the Orange County novitiate of the St. Michael Abbey of Csornai. The new foundation became an independent priory in 1975, and Prior László Keresztesy-Parker was consecrated as abbot in 1984. In 1990, he was re-elected as head of the abbey. He resigned from his position in June 1995 at the age of 75.

Under his leadership, the community grew significantly stronger: by the time of his retirement, it consisted of 41 priests and 60 novices. After his retirement, he lived among his fellow monks. He passed away in the United States and was laid to rest there.

History of the Hungarian Norbertines, é.n.