The Transport Accident Investigation Commission (TAIC) launched an inquiry after the skydivers plunged into Lake Wakatipu on January 10.
The NZONE jumpmaster was rescued from the lake by Philip and Kate Rive, of Cecil Peak Station, who drove a motor boat out to him shortly after the crash.
After an extensive sonar search of the area by the Police National Dive Squad, the body of 27-year-old American tennis coach Tyler Nii was not found.
The dive squad searched a 300m radius from where the jumpmaster was pulled from the lake and to a depth of 340m.
Peter Northcote, general manager of communications and investigation support at the TAIC, said: ``Our inquiry is nearing the end of the evidence-gathering phase, while preliminary evidence analysis has also begun.
``For legal reasons we cannot discuss the detail of this work for any specific inquiry beyond these general descriptions.''
Mr Northcote said TAIC had not yet issued any recommendations or interim reports as part of the ongoing inquiry.
The Civil Aviation Authority (CAA) is still investigating the incident.
CAA senior communications adviser Philippa Lagan said the authority expected the investigation to be finished some time next year.
She said the CAA could not comment further on the investigation at this stage.
