The coronial inquest into the case of Lucille Butterworth formally opened in Hobart this morning.

Miss Butterworth was last seen alive at a Claremont bus stop on August 25, 1969.

It is one of Tasmania's oldest unsolved murders.

The coroner has the power to hold an inquest if a death is suspected.

''I do suspect homicide,'' Mr Cooper said.

''The fact that absolutely no trace has ever been found...the only reasonable conclusion is that Miss Butterworth is dead,'' he said.

Mr Cooper said there were four persons of interest, three of which were still alive.

''Most, but not all, are able to be excluded from having something to do with her disappearance''.

''I urge anyone who has any information to make contact with the coroner's office,'' he said.

Hearings begin on August 31.