Peter Antonellis, a compliance officer with the state’s Office of Elder Affairs who has been highly critical of the agency’s oversight of assisted living residences, was told on Tuesday morning to pack up his things and leave the state office building where he works.

“You are hereby placed on paid administrative leave,” said a letter handed to him shortly after he arrived for work. “You shall remain on this leave pending the completion of an investigation into multiple instances of potentially inappropriate and unprofessional conduct.”

The letter, signed by Assistant Elder Affairs Secretary Susan Temper, did not identify the alleged inappropriate or unprofessional conduct. It also warned Antonellis about interfering with the investigation.

“If it is discovered that you have attempted to interfere with or undermine the agency’s ability to conduct the investigation, then you will be subject to immediate discipline up to and including termination,” the letter said.

Antonellis said he had not been informed what he had done wrong, but he had no regrets about speaking out about shortcomings at the agency. He indicated he believes the agency’s real concern is his raising concerns in the first place.

“Elder Affairs will do whatever they need to do to protect themselves, and they won’t have any hesitation to bury me or malign me,” he said.

John Polanowicz, the state secretary of health and human services, the parent agency of Elder Affairs, said a few weeks ago that he had no problem with Antonellis raising concerns. “Any employee that has an issue or concern is absolutely encouraged to bring those issues up,” he said.

Martina Jackson, a spokesperson for Elder Affairs, declined comment. “We can’t comment on an ongoing personnel matter,” she said. Alec Loftus, communications director for the parent agency of Elder Affairs, said the state is investigating “a potential health information privacy violation.”

Antonellis is a rarity on Beacon Hill, a state employee who speaks out publicly about the shortcomings of the agency he works at. He told CommonWealth that Elder Affairs does almost no analysis of the information it gathers on seniors who fall down, wander off, or are abused or exploited. He also shared internal emails and documents indicating Elder Affairs let an Athol facility operate as an assisted living residence even though it wasn’t certified and unsafe.

He also told the Boston Globe that “most elders and their families think this is a regulated industry, but we don’t have the staff to regulate it.”