A coalition of trade unions is putting up a 100-thousand dollar reward for tips that lead to an arrest in connection with a noose found hanging at a construction site in Altoona. Earl Agan is president of the Central Iowa Building Trades.

The noose was found at the Facebook Data Center. Investigators believe it was put there on Juneteenth, the holiday that marks the end of slavery in America.

The reward offer expires September 1st. Agan says 50-thousand dollars will be paid if a tip leads to the arrest of a person or persons. The other half of the reward will be paid if there’s a conviction.