The family believe the church played a major role in his death but have spent the past two years without answers or recourse.
Now they've urged the federal government to initiate an inquiry into the controversial religious group, under fire following recent allegations of blackmail, sanctioned beatings, forced abortions and financial fraud.
Independent senator Nick Xenophon last week made a scathing parliamentary attack on Scientology, accusing it of using religion as a front for criminal activities.
He wants the organisation to be investigated by parliament - a call which has so far won the backing of the Australian Greens, but not the government or opposition.
Senator Xenophon and Greens leader Bob Brown on Monday flanked Mr McBride's brother Stephen as he appealed directly to the prime minister to support a formal inquiry.
Police investigating his younger brother's death in 2007 had been stymied by the church, which failed to provide personal audit files as requested, Stephen McBride said.
"Every time I think of Scientology I still get a real bad aftertaste in my mouth," he told reporters in Canberra.
"There's something just not right about it."
Mr McBride was adamant the church contributed to his brother's suicide, with the coroner reporting the telephone messages contained intimidating statements, such as "this behaviour is unacceptable" and "you have missed your interview".
He had spent $25,000 on Scientology courses in his time with the church.
"The bombardment of 19 telephone messages backed him into a corner with no room to breathe," Mr McBride said.
"We've been through hell the last two years - please don't let my brother's death be in vain."
Senator Xenophon has yet to win the support of the government, despite Prime Minister Kevin Rudd saying last week he also had concerns about Scientology.
"It doesn't seem the numbers are there yet, but I will continue to build my case," he said, adding this was not a crusade against freedom of religion.
"This is a hell of a week and I think we are distracted with other issues, but I think it's inevitable there will be an inquiry one way or the other."
Senator Brown, who labelled Scientology a cult, said he would be angry if the government and coalition quashed any move for an inquiry.
aap 23 Nov 2009
Scientology - a 'cult' created by Lafayette Ronald Hubbard in order to avoid tax.
There is nothing 'religious' about it.