Darren Erman was fired by the Golden State Warriors earlier this month for a "violation of company policy."
Erman was secretly recording conversations between the Warriors' coaches and players.
Sources said Erman, who was coach Mark Jackson's second assistant, would record coaches' meetings, meetings between the coaches and players, and informal discussions among coaches that took place in the team's coaches room -- all without the participants' knowledge.
"He was taping everything," one source said. "Taping pregame speeches wouldn't have been that bad, but he was taping guys just sitting around talking in the coaches' office."
Erman would be present during the tapings at some points, but he would leave his phone behind to record conversations other coaches were having without him present.
The Warriors' other coaches began noticing a change in Erman's demeanor and behavior in March, a source said. A few weeks later, they discovered that he was recording them.
Erman was hired by the Boston Celtics on Tuesday as Director of NBA Scouting.