Department worker Abdul "Alex" Aziz El-Debel and IT consultant Raminder Singh Kahlon are accused of working with Gopalakrishnan Suryanarayanan Vilayur to influence or corrupt the department's IT procurement processes relating to contractual projects.

The result, during the alleged conspiracy between March 2019 and June 2020, was the favouring of candidates at New Horizons Business Solutions, owned by Kahlon, and Algoram, owned by Vilayur, who is not on trial.

As part of the agreement, a portion of the share of the margins the businesses received would be paid to El-Debel.

El-Debel and Kahlon have pleaded not guilty and have stood trial in the ACT Supreme Court since June 6.

In her closing address on Monday, El-Debel's barrister Catherine Newman said the case rises or falls on the money to her client because the prosecution conceded that any influencing of the procurement processes was not itself criminal.

"You've heard the Crown admit they can't prove a single dollar was ever paid to Alex," she said.

"The Crown is clutching at straws. On my submission, it [case] falls.

"The evidence about the alleged money is so tenuous, so unreliable and open to so many interpretations."

Ms Newman said the prosecution relied on only one call involving El-Debel driving to Sydney to visit his mother who had suffered a fall before he picked up an item, which the prosecution alleges was cash, from another person.

She argued that the item was related to El-Debel and Kahlon building an app and that if her client were part of a conspiracy, there would be more intercepts showing discussions about such a matter.

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Ms Newman said that during cross examination of federal agent Stephen Gibson, the lead investigator of the case, he conceded that only 60 of the more than 60,000 communication intercepts involving El-Debel were included in the brief of evidence to the prosecution.

"Mr Gibson also conceded he could not be sure that all relevant calls, including those that might've assisted Alex in his defence, was ever disclosed to us," she said.

Among her other major points was El-Debel's conflict-of-interest declarations about his relationships with Vilayur and Kahlon related to two procurements.

"[There was] an abundance of evidence that the people who were on the evaluation panels [related to candidates], even those put forward by Alex, exercised their roles properly and impartially," Ms Newman said.

She said the underlying motivation for her client was not a dishonest one but one, in consultation with senior management, to obtain the best candidates for the department.

During trial, Commonwealth prosecutor David Staehli SC argued that the department ultimately recruiting personnel from New Horizons and Algoram meant "large sums" of money flowing to the companies.

"It was the environment of the department ... there appears to be somewhat of a hothouse in relation to the amount of work that was on hand," Mr Staehli said.

Mr Staehli argued the Algoram name was significant because it combined the first syllables of each of the three men's first names - being Alex in El-Debel's case - that went towards establishing the conspiracy.

He said the candidates put forward by the two businesses meant those candidates were in better positions than if other companies had put them forward.

The trial heard the contracts awarded to the businesses represented only a small portion of about $25m worth of IT contracts at the department at the time.

After four weeks of evidence, including public service workers' testimonies and financial documents, the jury will begin its deliberations on Tuesday.

For a guilty verdict, the jury needs to be satisfied beyond reasonable doubt that the trio agreed and pursuant to that agreement is that a portion of the share of the margins the businesses received would be paid to El-Debel.

AS IT HAPPENED

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