Neugebauer -- whose public dressing down of the federal worker at the World War II Memorial was caught on video and became a hot topic on cable news and online -- offered the apology in a letter to National Park Service Director Jonathan Jarvis, CNN reported Saturday.
In the Oct. 2 confrontation -- one day after the federal government shutdown began – Neugebauer berated the ranger because military veterans were unable to visit the memorial.
"How do you deny them access? I don't get that," he said.
"It's difficult," said the park ranger, who the Park Service said wished to remain anonymous.
"It should be difficult," Neugebauer said.
"It is difficult. I'm sorry, sir," she answered.
"The Park Service should be ashamed of themselves," he said.
"I'm not ashamed," the ranger said.
"Well you should be," Neugebauer said as he walked away from the ranger.
Heather Vaughan, a spokeswoman for Neugebauer, said he attempted to apologize to the ranger but the Park Service preferred he send the apology to Jarvis.
"I regret how I handled that situation, and I would like to offer you my apologies," he wrote in a letter dated Oct. 17.
"I'm sorry for the way I spoke, not only because I put the Ranger on duty in an uncomfortable position, but also because my remarks were not an accurate reflection of the regard I have for the Park Service," he wrote.