KANSAS CITY, KAN. ? Prosecutors concluded their case Thursday in the federal fraud trial of former Westar Energy Inc. chief executive David Wittig.

Attorneys for Wittig and his co-defendant, former Westar executive vice president and chief strategy officer Douglas Lake, will begin their case today and could take at least two weeks. The case began on Oct. 19 and was expected to last 10 weeks.

Wittig and Lake are accused of looting Westar, the largest electric utility in Kansas. Each faces 40 counts and at least 10 years in prison if convicted.

Among the charges is that they used company aircraft for personal travel, falsified corporate filings, manipulated company policies to give themselves larger bonuses and other benefits, and pushed the company toward a deal that would have merged Westar with a New Mexico utility and netted the two men millions of dollars.

Wittig and Lake deny any wrongdoing, saying their actions were legal and approved by the company’s board of directors.

On Thursday, defense attorneys completed cross-examining prosecution witness Jim Zakoura, an attorney who represents many of Westar’s large industrial electric customers and who testified Wednesday that Wittig tried to hide parts of his compensation from shareholders.

He also testified that between 1999 and 2002, Wittig took 110 trips on corporate aircraft with family members while Lake took 144 trips with family members.

Under questioning by Lake’s attorney, Edward Little, Zakoura on Thursday acknowledged that many Westar employees took their family members for trips on the company airplanes, not just Wittig and Lake.

However, Zakoura added that the two men appeared to do it more often than others.

Both Little and Wittig’s attorney, Adam Hoffinger, repeatedly stressed that while prosecutors questioned payments Wittig and Lake would have received if the merger deal had gone through, the merger was stopped by Kansas regulators and the payments never made.