The mother of a two-year-old boy killed by his father in Lismore on Sunday says the toddler should have been able to trust the man who took his life, and she will love and miss the little boy forever.

“Our family is facing incomprehensible grief. Our beloved Rowan was taken from us in the most unfathomable way,” Lismore doctor Sophie Roome said in a statement she issued with her family.

“Rowan’s life was ended by an evil and cowardly act of violence, perpetrated by a person he should have been able to trust the most. There are no possible excuses for this hurt, and no end to the pain it has caused.”

Police found the bodies of James Harrison, 38, and his two-year-old son, Rowan, inside Harrison’s unit at East Lismore in the NSW Northern Rivers on Sunday night. Rowan had been visiting his father at the unit, where Harrison lived alone.

“Rowan was a beautiful, joyful, and adored little boy. He had so many amazing qualities, and his short life was filled with rich and happy experiences,” Roome and her family said in the statement.

“He loved music, the beach, swimming, his friends and his family. He touched the hearts of everyone lucky enough to be in his world.

“We are devastated. We will love and miss Rowan forever. We thank all those who have provided support, and we acknowledge the suffering of James’ family, which is also immense.”

Roome rang police and raised the alarm on Sunday when Harrison did not return the little boy at 4.30pm, as scheduled.