(Reuters) – A tree trimming company has been handed the largest penalty imposed in a United States immigration case, totaling $95 million, after pleading guilty to employing illegal immigrants, the U.S. Attorney’s Office said.

Immigration reform is a major political issue in the U.S., with President Donald Trump saying he will crack down on illegal immigrants and build a wall between the United States and Mexico in order to reduce illegal border crossings.

Asplundh Tree Experts, Co., which trims trees and clears brush for power and gas lines across the country, hired employees who provided fake identification documents from 2010 to 2014, the U.S. Attorney’s Office in Philadelphia said.

The prosecutor said on Thursday that Asplundh’s management were “willfully blind”, while supervisors and general foremen hired illegal immigrants through word of mouth referrals.

“This decentralized model tacitly perpetuated fraudulent hiring practices that, in turn, maximized productivity and profit,” it said.

The company’s chairman and CEO Scott Asplundh said in a statement that it has taken steps to improve its hiring practices, including reviewing the identification of all employees.

“We accept responsibility for the charges as outlined, and we apologize to our customers, associates and all other stakeholders for what has occurred,” he said.