John Russell, returned from serving in France, disappeared from the ferry taking him from Wellington to Lyttleton (near Christchurch) for convalescence at Hanmer Springs, under escort. A Court of Enquiry was set up to see if the Military Authorities were to blame for his disappearance. It was not a coroners court, and death was not established. It does, however, seem likely that, given his service record gives “drowned” as his cause of death, that he did jump or fall  from the boat.

FINDING IN THE RUSSELL CASE. WELLINGTON, June 20. 

The finding of the Court of Enquiry into the circumstances connected with the disappearance of Rifleman John Russell,  returned soldier, from the Mararoa during a voyage from Wellington to Lyttelton on October 24th and 25th, 1918, was made public to-day. The Court finds it reasonable to suppose that Russell lost his life during the voyage. His mental and physical condition was such as to necessitate a special escort being detailed to ensure his safety on the voyage. The first escort, Sapper Goodwin, did not discharge his duties efficiently, but the second escort did. "With the exception of Goodwin, no member of the New Zealand military forces was guilty of negligence, or in any other way culpable in connexion with Russell's disappearance.”

[Press, Volume LV, Issue 16555, 21 June 1919, Page 4]