A large collection of floral tributes piled up outside St Andrew's Cathedral School in Sydney's city centre on Monday morning as students, teachers and parents arrived.
Sports assistant Lilie James, 21, was found dead with horrific head injuries inside the campus gymnasium toilets just before midnight last Wednesday.
The grandmother of Lilie James described her as a "beautiful young woman".
The school was closed to students for the rest of the week, except for those sitting Year 12 exams.
On-site counsellors have been made available for teachers and pupils who gathered for a school assembly to honour the much-loved coach.
Head of School Julie McGonigle thanked students and parents for the love, support and kindness shown to staff and each other.
"The tight-knit, deeply loving and faith-filled nature of our community is what will get us through this and you have demonstrated that in its fullness over these last days," she said.
"You are not alone in this, we are a strong and courageous community.
"Together, each day, we can face our fears and take a step forward, (and) together we can rise up with courage and strength, for the Lord our God will be with us wherever we go."
A Go Fund Me page set up on behalf of Ms James' family has raised more than $16,000.
Her grandmother Barbara thanked the public for supporting the family and described Ms James as a "beautiful young woman".
"We just cannot understand why this would happen to her," she told 2GB.
"(She was) so full of life and never stopped. She went to uni. She worked four-and-a-half days a week. She coached swimming. She coached water polo. She played water polo.
"Some people come into this world, I think they're so special and they don't stay long. That was my granddaughter."
Paul Thijssen, a 24-year-old sports coach at the school, was wanted for questioning over Ms James' death.
The pair had reportedly been in a relationship for a few weeks in the lead-up to the death.
Police retrieved a body from the water near a clifftop park in Sydney's east.
Police recovered a body on Friday near the base of cliffs at Vaucluse, in Sydney's eastern suburbs, where items linked to the suspected murder were found the previous morning.
Police said it was a man's body but he was yet to be formally identified.
Detectives previously said they were looking at the possibility Thijssen had taken his own life after Ms James' death and they were not looking for any other suspects.
Dr McGonigle said the school community had been left with grief, shock and utter confusion because they knew both Ms James and Thijssen.
"Our beautiful Ms James, a ray of light, and Mr Thijssen, whose actions are completely incongruent with who we knew," she said.
She encouraged students to focus on three simple steps each day: ask for help, be kind and carry on with courage.
"Every emotion you are feeling is valid and it is important to talk about them. Ask for help whenever you need it, now or in the times to come," she said.
"Courage is not an absence of fear, it is taking a step forward in spite of our fears."
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