SOUTH PORTLAND — Sen. Susan Collins on Friday defended her decision to vote to acquit President Trump during his Senate impeachment trial this week, but she declined to respond to questions later in the day about the sudden ouster of two key impeachment witnesses who testified against the president.

In her first public appearance in Maine since the trial ended Wednesday, Collins spoke at a chiefs of police conference in South Portland before answering questions from the media in which she condemned the notion of retribution against witnesses who came forward and defended her voting record.

By the end of the day, the Trump administration had removed Army Lt. Col. Alexander Vindman and his twin brother, Lt. Col. Yevgeny Vindman, both of whom worked for the National Security Council in the White House. Later Friday, European Union Ambassador Gordon Sondland announced that he was being recalled to Washington. Sondland and Alexander Vindman testified during the House impeachment hearings against Trump.

“I think it’s important to understand that when you’re in an impeachment trial, you consider the evidence that is before you,” Collins, a Republican, said after an event in South Portland. “You don’t try to make predictions. You consider the evidence that’s before you. In this case, the evidence did not meet the high bar that’s established by the Constitution for immediate removal of the president from office. So that was the basis for my decision.”

She then added: “I obviously am not in favor of any kind of retribution against anyone who came forward with evidence.”

Three inquiries to Collins’ office regarding the firings went unanswered Friday night, including questions about whether Collins would take any action following the removals, or whether she believes the administration’s actions were in fact retaliatory. She also did not respond to a question about whether she believes the reassignments would have a chilling effect on other career civil servants who work in proximity to power and who may be called to testify in the future.

Earlier in the day during her remarks, she emphasized ways that she has pushed back against Trump, mentioning her support for a resolve that would ensure he receives congressional approval before embarking on certain military action and also her opposition to diverting military funds to pay for a border wall.

“I raise those examples because they are examples of where I’ve voted to curb the president’s powers and will continue to do so,” she said. “There is always friction between the executive and the legislative branch no matter who is president.”

Lt. Col. Alexander Vindman was dismissed and escorted out of the White House complex on Friday afternoon, according to his lawyer, who said he was asked to leave in retaliation for “telling the truth.”

“The truth has cost Lt. Col. Alexander Vindman his job, his career and his privacy,” David Pressman, an attorney for Vindman, said in a statement.

“He did what any member of our military is charged with doing every day: he followed orders, he obeyed his oath and he served his country, even when doing so was fraught with danger and personal peril,” Pressman said. “And for that, the most powerful man in the world – buoyed by the silent, the pliable, and the complicit – has decided to exact revenge.”

The White House did not respond to Pressman’s accusation.

Vindman and his brother were reassigned to the Army.

Sondland issued a statement about his dismissal.

“I was advised today that the president intends to recall me effective immediately as United States ambassador to the European Union,” Sondland said.

Collins spoke Friday at a meeting of the Maine Chiefs of Police Association and drew laughs when she said it was “wonderful to be away from Washington.” She then talked about the opioid crisis and its impact on law enforcement, and also about the growing threat of fraud and scams for seniors, something she’s worked on as chair of the Senate’s Aging Committee. Collins also disclosed to the group that she has received three credible death threats since her vote this week, which are being investigated by the FBI. Her staff would not provide any additional details.

Collins’ Maine offices were besieged by protesters during the impeachment proceedings, but none was on hand in South Portland on Friday morning.

After her speech, Collins was asked about her vote to acquit the president. She again said that she wished that witnesses had been called.

“I voted to hear additional witnesses. I thought there should be a limited number chosen by each side in the interest of fairness and I’m sorry that was defeated,” she said, referencing Sondland and former National Security Adviser John Bolton as voices she would have liked to have heard from. “The reason a few additional witnesses would have been helpful is that there were inconsistencies and gaps in the hearing records that they might have been able to resolve.”

“I think what has been lost in this debate is: This is not a vote on whether you like the president or you dislike the president, whether you support his policies or whether you oppose his policies, whether you would prefer that his conduct were more more elevated or whether you agree with how he presents himself,” Collins continued. “This was a vote on the evidence presented by the House … of whether they met the very high bar of bribery, treason, high crimes and misdemeanors that is set forth in the constitution.”

Collins did not answer whether she would support Trump’s reelection but later told the Sun Journal after an event in Lewiston that she has not made up her mind.

“I haven’t even given thought to presidential politics,” she said.