HOUSTON -- Enron's ex-treasurer said Thursday he could not recall any notes or other tangible proof to tie former CEO Jeffrey Skilling to fraud and conspiracy at the company.

Ben Glisan is the only former Enron executive to go straight to prison after pleading guilty to a crime.

He's testified that Skilling backed fraudulent setups as a way to circumvent accounting rules that would disclose Enron's financial weakness.

Under intense cross-examination by Skilling's attorney on Thursday, Glisan said he had no notes or e-mails to back that testimony.

However, he assured "the conversations were quite memorable" and stood by his assertions that Enron's management misled investors about the health of the company.

Glisan is serving a five-year prison term after pleading guilty to conspiracy in September 2003.

The former treasurer's testimony Wednesday backed that of other government witnesses.

Glisan said Enron founder Kenneth Lay misled investors and employees with upbeat statements about Enron, even after Glisan told him the company faced financial disaster.

Glisan is the last major government witness in its case against Lay and Skilling. Prosecutors have said they hope to wind up their case with a few more witnesses next week.

Skilling and Lay are on trial in a Houston federal court on fraud and conspiracy charges.

Skilling faces 31 counts of fraud, conspiracy, insider trading and lying to auditors for allegedly lying about Enron's financial strength.

Lay faces seven counts of fraud and conspiracy for perpetuating the alleged scheme after Skilling resigned in August 2001.

Both men have pleaded not guilty.

If convicted, each could face decades in prison and millions of dollars in penalties.