Hi,
Just a bit of info regarding his wife listing herself as a widow on census.

There was a condition set back then, that if a husband was gone (lost, disappeared, transported) and the wife had no expectation of his return,,,then after 7 years she could have him legally classed as dead.
That was so she was free to remarry instead of having to support herself and children alone.

This was even more easy for convict wifes,,,whose husbands had long sentences,,,as it was assured he would NOT be returning within the 7 years.

The WA BDM's are online
http://www.bdm.dotag.wa.gov.au/_apps/pioneersindex/default.a...

Reverse Marriage Search
http://www.wamarriage.info/

If you think you know which death is his,,just google the town (town~cemetery) and you may find the cemetery. They have alot of cemeteries online now.

Kellie