TRENTON, N.J. — A former lumber company salesman has admitted his role in a scheme to defraud customers and lying about it to a federal grand jury.

Adam Martignetti faces up to 25 years in prison when he’s sentenced Sept. 28. The 43-year-old South River man pleaded guilty Monday conspiracy to commit wire fraud and making false declarations before a grand jury.

Martignetti worked for Linden-based Bayway Lumber. He conspired with others from 2011-2013 to give free items to customers’ employees and then recovered the cost of those items and made additional profits through overbilling and fraudulent billing.

Federal prosecutors say some of the affected clients included Amtrak and the city of Elizabeth. They also say the firm routinely provided New York’s Con Edison with lower-quality wood than it ordered and paid for.