The federal government’s criminal prosecution of Sen. Ted Stevens (R-Alaska) ran hot and cold last week — literally.

[IMGCAP(1)]An apparent problem with the thermostats in courtroom 24 of the E. Barrett Prettyman Federal Courthouse left the room frigid by Wednesday night, when the government’s case appeared to be teetering on the verge of collapse.

But prosecutors and courthouse maintenance staged a comeback the next day, and by Thursday afternoon, the courtroom was temperate and the government appeared to have re-established the theory of its case — that Stevens must have known workers from his pal’s oil services company were spending hundreds of hours on an extreme makeover of his home and that the Senator wasn’t paying for any of it.

Strangely, the government’s listing case appeared to have been righted by a witness prosecutors had not intended to call.

By Wednesday night, the government’s case appeared on the brink of collapse because of prosecutors’ repeated mishandling of evidence.

Judge Emmet Sullivan railed against prosecutors for repeatedly failing to provide exculpatory evidence to the defense, suggesting the government had tried to intentionally bury some evidence and had allowed a witness to enter evidence into the case that the government knew was false. As he had the week before, Sullivan considered a defense motion to dismiss the case.

Instead, he decided to strike key evidence from the record — including evidence the government had offered to establish the hours that workers spent renovating Stevens’ home.

What seemed even more daunting for prosecutors was Sullivan’s announcement that he would tell the jury that the government had intentionally presented false evidence, a statement that probably would raise doubts in the minds of the jurors about the rest of the case against Stevens.

But in the frosty courtroom Thursday morning, even the judge’s temper appeared to have cooled.

He agreed to soften the language of his instruction to the jury, essentially eliminating the reference to false evidence, and allowed prosecutors to call one last witness, despite their indication the night before that they had finished their case.

That decision outraged the defense.

Lead defense attorney Brendan Sullivan punched his right fist into his left palm and threw his arms up in exasperation.

Defense attorney Robert Cary told the judge that he was allowing the prosecution to paper over a serious violation of Stevens’ rights. “They were sanctioned for their conduct,” Cary said, but now “they want to reverse, rewind and pretend like it never happened.”

It quickly became clear why the defense was so upset.

The prosecution called Dave Anderson, a former welder for VECO, the oil services company owned by his uncle Bill Allen. It was Anderson’s timesheets that the judge had stricken from the record.

Anderson spent nearly two hours narrating a slide show of the renovation project at Stevens’ home, while chilled jurors in shawls and heavy coats shifted in their seats to keep warm. Anderson detailed the months that he and other VECO employees spent jacking up the house, leveling the land, pouring a concrete foundation for a new garage, welding supports for a new second-floor deck and installing a bedroom balcony and fire escape. Backhoes and other heavy construction equipment lurked in the background of the photos.

Coupled with the dozens of e-mails that the prosecution had already presented in which friends kept Stevens informed about the details of the progress of the work on his house, the evidence cast a shadow on the Senator’s contention that he did not know VECO workers were dedicating hundreds of hours to the project.

The prosecution rested and the defense began its case, which appears to be aimed partly at establishing that Stevens paid a fair price for the renovations and partly at having high-profile witnesses testify to the Senator’s overall integrity.

By Friday afternoon, the defense was in full swing, and the judge said to the jury, “We’re still working on the temperature here, it’s a little bit warmer.”

Some of that warmth apparently was the radiance of the star defense witness, former Secretary of State Colin Powell.

With Powell’s arrival, spectators filled the courtroom, and the general offered a fiery defense of Stevens. Powell said Stevens’ reputation is, “in a word, sterling.”

Powell said that throughout the 1980s, when he held several senior military positions that required him to work closely with Congress, he frequently dealt with Stevens. Powell said Stevens was direct and straightforward and would stand by any agreement he had made. There was “never any suggestion that he would be doing anything that was in any way improper,” Powell said.

“He fights for his state, he fights for his people, but at the same time he has the best interests of his country at heart.”

Powell said that in the terms of the infantry ranks from which he rose, “this is a guy you take on a long patrol.”

While it was delivered to a smaller audience, the more significant testimony might have been that of Tony Hannah, the contractor whom Stevens paid about $3,700 to raise the house 10 feet. Anderson had described this portion of the work the day before, explaining how he had loosened the bolts underneath the house, installed the jacks to raise it and built the new first-floor walls to place the house back down on.

But Hannah said he had loosened the bolts and done the other preparatory work for raising the house. After it was up in the air, he said, he had to come back several times before lowering the house back down because each time he returned, the first-floor walls were incomplete.

He said the job would normally take a week to 10 days, but Stevens’ house took about five weeks. And he said he did not recall ever meeting Anderson.

Stevens’ team also called two officials from the Anchorage assessors office to testify Friday. The official who assessed the Senator’s house after the renovations testified that she evaluated the upgrade as adding $106,000 to the home’s value, and she said she evaluated that work as “C+” quality. The other official testified that the assessed value of Stevens home rose from $87,500 before the renovations to $192,300 afterward.

The prosecution has argued that VECO and Allen spent about $188,000 on the renovations that Stevens did not repay and did not disclose as a gift. But the defense has noted that Stevens paid other contractors about $160,000 for working on the house. Stevens’ attorneys have argued before the judge — and are likely to make this point in closing — that because he paid $160,000 and the value of his house increased by a little more than $100,000, there was no reason for the Senator to assume that he had not paid the full cost of the renovation work. And because he paid more than the value increase, he received no gifts.

As the fortunes of his defense have risen and fallen, Stevens has remained stoic throughout. He has barely smiled, chatted only occasionally with his legal counsel and generally passively watched testimony or occasionally taken notes.

He has chatted with courtroom sketch artists during breaks in the proceedings, and on Friday he exchanged silent waves with some of his Alaskan neighbors as they departed the witness chair to head back to the Last Frontier, where the cold is more predictable.

Stevens’ defense is likely to call about a dozen more witnesses before it rests, including Sen. Orrin Hatch (R-Utah), and the case may be before the jury by midweek.