Documents revealing that a former senior adviser to Brian Mulroney received $90,000 from a company controlled by Karlheinz Schreiber in 1988 appear to contradict sworn testimony he gave earlier this week.

Copies of invoices and cheques obtained by The Fifth Estate show that Fred Doucet received the money less than three months after he left the Conservative government and before he registered as a lobbyist for the German-Canadian businessman.

It is unclear what services Doucet, who formally advised Mulroney from 1983 to 1987 but stayed in close touch with him afterward, provided for the money.

Doucet was contacted by The Fifth Estate Wednesday night, and when told the CBC had the invoice he sent to Schreiber for the $90,000, Doucet replied, "Why do you have that? What right do you have to have that?"

Although Doucet agreed to review the invoices and provide CBC News with a comment on Wednesday night, he did not reply.

The documents obtained by The Fifth Estate originated from sources in Germany, where more than a decade ago authorities raided Schreiber's business and residences just outside of Munich. Schreiber is fighting extradition to Germany where he faces fraud and other charges.

Doucet had testified to the federal ethics committee investigating the dealings between Mulroney and Schreiber that he first met Schreiber in the fall of 1988 and later registered as a lobbyist for Schreiber's company in the fall of 1989.

Lobby registry documents show that Doucet did register as a lobbyist for Schreiber's company Bitucan on Oct. 10, 1989.

Doucet also testified that he began working for Schreiber in the winter of 1990.

"I believe I got on the payroll in February of '90," Doucet told the committee.

But the invoice obtained by The Fifth Estate shows that Doucet's lobbying company, FDCI, billed Schreiber's company Bitucan "for professional services" on Nov. 2, 1988, for $90,000.

The money Doucet apparently received matches the same amount paid to four other lobbyists the same month.

On Nov. 15, 1988, Bitucan Holdings wrote cheques to: former Newfoundland premier Frank Moores, Gerry Doucet, Fred Doucet's brother, and Gary Ouellet, a former chief of staff to a Conservative transport minister.

The lobby firm Government Consultants International, GCI also received $250,000 from Bitucan on the same day.

Contacted Wednesday night, ethics committee chair Paul Szabo said it was possible that Doucet may have misspoke when he said he didn't lobby for Schreiber until late 1989.

"The relationship was before the dates that he testified to and would need clarification," said Szabo, "I don't have much choice but to raise it."