Glee actress Naya Rivera shouted for help in the seconds before she drowned, it has emerged.

The 34-year-old's body was recovered from Lake Piru near Los Angeles in July, days after she disappeared while out on the water with her four-year-old son Josey.

Previous police reports indicated that Rivera had helped Josey back to the safety of the boat after they had encountered difficulties while swimming, and now the investigative and autopsy report has shed more light on the fatal incident.

According to E!, the report reveals that Josey told police that he and his mother had jumped into the lake on the count of three.

The report continues: "Shortly after they jumped in the water, the decedent told Josey to get back on the boat. She helped him onto the boat and he then heard the decedent yell 'help' and she put her arm in the air. She then disappeared into the water."

Rivera's cause of death was determined to be accidental drowning.