A construction worker who became a witness in a federal workplace safety investigation after he was injured during the collapse of a new Hard Rock Hotel in New Orleans was deported by the immigration authorities on Friday, his lawyers said.

The worker, Delmer Joel Ramirez Palma, had to scramble to stay alive while metal and debris rained down and parts of the 18-story structure pancaked around him and killed three of his colleagues on Oct. 12.

Mr. Ramirez Palma had raised concerns about problems with the construction with supervisors multiple times, according to his lawyers. After the building crumbled around him, he gave an on-air account to a Spanish-language news outlet and became a plaintiff in a lawsuit against the developers of the project and their construction firms, accusing them of using substandard materials and inadequate underpinnings to shore up the concrete floors.

On Oct. 14, two days after the collapse, Mr. Ramirez Palma, an immigrant from Honduras who was not authorized to remain in the country, was arrested while on a fishing trip and then detained by Immigration and Customs Enforcement.

During his time in immigration detention, federal investigators examining what happened at the site of the $85 million hotel project, just steps from the city’s French Quarter, interviewed him on three occasions.

But even as one arm of the federal government sought his help, another pressed ahead with his deportation, in a move that New Orleans officials, immigration advocates and labor lawyers said could have a chilling effect on immigrant workers who encounter safety violations and could also hamper the investigation into the Hard Rock Hotel collapse.

“We must not deter victims and witnesses of construction catastrophes from coming forward,” the New Orleans City Council president, Helena Moreno, and vice president, Jason Williams, said in a statement this week.

An ICE official said there was no connection between Mr. Ramirez Palma’s deportation and his emergence as a plaintiff in the lawsuit or as a witness in the investigation by the Occupational Safety and Health Administration.

Both ICE and Mary Yanik, a lawyer with the New Orleans Workers’ Center for Racial Justice who has been working on Mr. Ramirez Palma’s case, confirmed his deportation on Friday.

“Delmer Joel Ramirez Palma’s deportation leaves every one of us less safe,” the workers’ center said in a statement late Friday. “The next time a building collapses, we will wonder if it could have been prevented if our federal agencies had prioritized answers and accountability for the survivors of the Hard Rock, we will wonder if the same bad actors are to blame, and we will wonder if potential whistle-blowers kept silent because they saw what happened to Joel.”

Mr. Ramirez Palma emigrated from Honduras in 1999 and never returned. He was not legally authorized to work in the United States, but he had spent nearly two decades in the construction business in New Orleans, his lawyers said. He is married and has a 10-year-old son.

A federal immigration judge ordered his deportation in 2016, but Mr. Ramirez Palma was able to stay because he showed that his removal would harm a United States citizen, his son. His latest application for an extension, filed in August, was denied the week before the partial collapse.

“Mr. Ramirez Palma is a material witness to a potentially criminal investigation,” said Daryl A. Gray, a partner at Wright Pichon & Gray, a New Orleans firm representing the workers in their lawsuit. “And he is being deported by the same government duty bound to uncover what caused this construction project to fail and kill and injure multiple human beings.”

Safety inquiries typically take at least six months before citations are issued and some whistle-blower investigations can last years.

“It’s certainly not appropriate to have an individual who is at the center of the beginning of a whistle-blower investigation whisked away to another country and be potentially very difficult to get in touch with,” said Michael D. Felsen, who was a lawyer in the Department of Labor’s office of the solicitor for 39 years before his retirement in 2018.

“It takes a lot of work to get to the truth,” he added. “And often the truth will not come out until the two opposing stories go to trial and a judge will have to decide.”

The whistle-blower and retaliation division of OSHA, which is an agency of the United States Department of Labor, has opened an investigation based on evidence Mr. Ramirez Palma shared. Retaliating against employees for claiming their rights under federal labor law is illegal, regardless of the worker’s immigration status.

Additionally, under a 2011 agreement between the Homeland Security Department and Labor, ICE should not arrest workers who are involved in disputes that are being investigated by the Labor Department.

Cases like this do not come up very often, experts said, but one dating to 2017 brought about a different result. An undocumented worker in Boston, also from Honduras, fell off a ladder and broke his leg. While OSHA began investigating, the Department of Labor found that the construction company tried to get the worker deported.

The worker was released from an ICE facility and now has work authorization. A court will soon decide the case against the construction company.

Mr. Ramirez Palma has suffered from headaches, inflamed internal organs, torn muscles, upper and lower back pain, and lapses in consciousness, his lawyers said.

His wife, Tania Bueso, said that other undocumented workers her husband had asked her to contact were now afraid to help in the OSHA investigation.

“I just want justice for him and for all the workers who want answers about what happened at the Hard Rock Hotel,” Ms. Bueso said.