Anyone who watched Donald Trump speak to the Detroit Economic Club on Monday noticed them. Whether you were there inside Cobo Center, watching online or on TV, it was impossible to ignore the protesters who disrupted the presidential candidate's policy speech on multiple occasions.

By our count, law enforcement and security personnel removed 14 people from the event.

But where did they come from? How did they get inside a private meeting of the city's Econ Club?

Today, the group's president and CEO explained it in a letter to members.

"A misguided 23-year-old man fraudulently bought a new membership and invited female guests to do his dirty work," Beth Chappell wrote.

In her letter to members of the Detroit Economic Club, Chappell said that man claimed to work for a company that had fired him two years before. He brought twenty guests, she said.

"Detroit was in the international spotlight yesterday and a knucklehead disrupts an historic speech? This is not reflective of our Club or our City," the letter states.

Read the complete letter to Detroit Economic Club members here: