Parliament voted to impeach Park last month over an influence-peddling scandal that has brought hundreds of thousands of protesters onto the streets every week demanding her removal.
At the time of the vote lawmakers also said allegations that Park failed to carry out her official duties as the head of state during the ferry sinking were also grounds for her removal from office.
The Constitutional Court last month urged Park's defence counsel to clarify the mystery surrounding her seven-hour absence during the disaster that claimed more than 300 lives, mostly school children.
Park's lawyers said today that she had felt unwell on the morning of the disaster and stayed at her residence instead of her office -- both within the presidential Blue House complex.
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They submitted documents to the Constitutional Court showing timelines of her receiving reports by phone or from her aides about the disaster and issuing directives.
But Justice Lee Jin-Sung, one of the nine members of the court, told Park's legal team that the timelines failed to clarify exactly when and how she first came to learn about the sinking.
Lee noted that TV channels broke the story just after 9:00 a.M. Local time and said Park should clarify whether or not she was watching the news at the time.
"(Park) received numerous phone calls from the chief of the National Security Office and gave orders," Lee Joong-hwan, a lawyer representing Park, told reporters on the sidelines of the hearing.
"She took appropriate steps."
However, representatives from parliament told the hearing that neither the top national security advisor nor the chief of the presidential secretariat knew where Park was at the time of the disaster.