Federal officials in Boston said on Thursday they charged 13 people in connection with a kickback scheme involving microcap stocks.

The defendants included corporate officers, lawyers and a stock promoter who allegedly used kickbacks and other tricks to gather investments for thinly traded stocks, according to a Justice Department statement.

The investigation included an undercover agent posing as an investment fund representative, authorities said.

The U.S. Securities and Exchange Commission also said it suspended trading in seven companies involved in the alleged scheme.

The case follows a year-long investigation into the microcap stock market, officials said. Defendants included individuals from Massachusetts to California. Charges included criminal and civil claims, including mail fraud, wire fraud, and conspiracy to commit securities fraud.

The Justice Department said defendants included Kelly Black-White, of Mesa, Arizona, and James Prange, of Greenbush, Wisconsin, both in the business of finding capital for emerging companies.

(Reporting by Ross Kerber, editing by Gerald E. McCormick)