A Prior Lake couple allegedly thought it would be “a good educational tool” for their son and his friends to learn how to make homemade explosives from PVC pipe and gunpowder.

They had no idea, they reportedly said, that the teens would go on a destructive spree, using pipe bombs to explode mailboxes in Burnsville, Lakeville and rural Scott County.

One of the incidents drew Bloomington’s bomb squad, according to charges.

The allegations surfaced in two criminal complaints filed last month by the Scott County attorney’s office against Robert and Roberta Masters, who each face felony charges of manufacturing explosives and aiding offenders in a felony.

Their first court appearance is scheduled for Nov. 2.

Robert Masters, 48, is suspected of accompanying his son last spring to Fleet Farm in Lakeville, where, over two visits, they bought 2 pounds of gunpowder using a credit card. The powder, which is used to arm muzzle-loading firearms, cannot be bought by anyone under the age of 18.

Masters then showed his son and his son’s friends how to assemble explosives on the family’s workbench, and he and his wife encouraged the teens to learn more by watching how-to videos on YouTube, according to the criminal complaints.

Not long afterward, mailboxes in Burnsville, Lakeville and Scott County began exploding.

Five teens are under suspicion of taking part in at least six bombings. A sixth is believed to have been a witness in at least one of them. The teens are identified solely by their initials in the complaints because they are juveniles.

One of the teens said the group began blowing up mailboxes at random but later targeted the homes of people they knew, the complaints said.

A woman answering the phone at the Masters’ residence Wednesday said, “I have nothing to say,” and hung up the phone.

The criminal complaints offer this version of events:

On May 30, a Scott County deputy investigated a mailbox that had been destroyed in Credit River Township, outside Prior Lake. The homeowner said that a week earlier, someone had thrown eggs at her house and placed on her front stoop a bag of paintballs, which had char burns as if it had been lit on fire. The homeowner’s daughter said the family was acquainted with her brother’s 16-year-old classmate, identified only as A.L.U. in charges. A.L.U.’s female friend had once approached her brother and asked about damage to his house.

On June 14, a Scott County deputy called in the Bloomington Police Department’s bomb squad to remove a 6- to 8-inch pipe bomb from another mailbox in New Market Township. In that incident, the homeowner’s son reported receiving a text message on his cell phone from his estranged 16-year-old girlfriend, initials L.J.L., which read: “fine, now I will have to do something to you and it won’t be TP … that’s for middle schoolers … I bet you live out on Red Fox Drive, don’t you” When questioned by police, the girl initially denied any involvement in the bombings, but later admitted she accompanied a group of teens as a spectator on three occasions, according to charges.

Police stopped by A.L.U’s home June 19 and found Roberta Masters, 52, there picking up her son. The criminal complaint states the mother told the teen not to talk to the detective, though he came to the door and answered questions anyway. That night, Robert Masters met with several parents of the other suspects in the bombings to coordinate what each family would tell police, according to charges. Witnesses later reported the couple said “they did not want the police to parent their child. … They also suggested getting all of the families together to tell them not to talk to police, to get their stories straight and make amends with all of the victims.” Roberta Masters allegedly told the group she “thought bomb making was educational and did not want to stifle her son’s curiosity.”