German-Canadian businessman Karlheinz Schreiber is promising to reveal something significant as he returns to Parliament Tuesday to testify about his dealings with former prime minister Brian Mulroney.

Schreiber, who has been fighting his extradition to Germany for eight years, also told CBC News he has been granted bail and will walk out of an Ottawa jail Tuesday morning.

Schreiber spent the weekend in the Ottawa Detention Centre studying documents he said he needed as a key witness for the federal ethics committee investigating his business relationship with the former prime minister.

The committee is looking into $300,000 in cash Mulroney accepted from Schreiber after he left office in 1993.

It's also reviewing Mulroney's $2.1-million settlement from the federal government in 1997 over his libel suit regarding the so-called Airbus affair — in which millions of dollars in secret commissions were paid in the sale of jets to Air Canada.

Last week, during his appearance before the committee, Schreiber offered some details about his relationship with Mulroney. He said Mulroney was only paid $300,000 of a $500,000 business deal because the former prime minister did not hold up his end of the bargain.

Schreiber also refused to answer questions, saying he didn't have enough time to go through his files before his appearance.

But Schreiber told CBC News on Monday that he will have so much to say on Tuesday, it'll be "like Christmas" for the committee.

Schreiber is also suing Mulroney to recoup the $300,000 in cash payments. Before last week's hearing, it was reported the money was allegedly paid for Mulroney to help establish a pasta business and a light-armoured vehicle factory, and that the services weren't provided. But Schreiber told the committee the cash arrangement had nothing to do with the pasta business.

Schreiber alleged in an affidavit that the deal was struck two days before Mulroney left office as prime minister in 1993.

Schreiber also alleged in the affidavit that a Mulroney adviser asked Schreiber to transfer money in connection with Air Canada's 1988 purchase of Airbus planes to a Mulroney lawyer based in Switzerland.

None of the allegations against Mulroney has been proven in court. 

'There's very little patience left': NDP MP

New Democrat MP Pat Martin said Schreiber, who frustrated the committee last week with his at-times coy responses, could face disciplinary action and even jail if his answers Tuesday don't satisfy members.

"I think the attitude of the committee is there's very little patience left," Martin told CBC News on Tuesday.

The fact that Schreiber could be free on bail before his appearance might play to the committee's advantage in its attempts to get him to speak, Martin added.

"If he's a free man again, the idea of going back to jail might be quite a good motivation to co-operate with the committee," he said.

If Schreiber is unco-operative, the committee could find him in contempt of Parliament and potentially order him returned to jail, said Joseph Maingot, former law clerk and parliamentary counsel.

"It means that you're insulting Parliament, you're not honouring Parliament, and so the furthest you can go with respect to that is to be incarcerated," Maingot told CBC News on Tuesday.  

Schreiber's allegations have spurred Prime Minister Stephen Harper to call a public inquiry into the affair.

Mulroney expected to testify before holidays

Talks continue on setting a date for Mulroney to appear before the committee. Members still expect him to testify before the holidays.

CBC News has also obtained a partial list of other potential committee witnesses including CBC Fifth Estate producer Harvey Cashore, whose documentaries have in part sparked the probe.

Other potential witnesses include authors Stevie Cameron and William Kaplan, both who have written books on Mulroney; former Mulroney spokesman Luc Lavoie; and John Crosbie and Elmer MacKay, two former Mulroney cabinet ministers.

Schreiber is wanted in Germany on charges of fraud, tax evasion and bribery.