The league is expected to gather relevant information to open its investigation against Houston, sources said.
Houston fired general manager Brian Gaine the night after New England's Super Bowl ring ceremony on June 6 at Robert Kraft's house. The Texans finished in first place in the AFC South with an 11-5 record last season.
Former Patriots team chaplain and current Texans executive vice president of team development Jack Easterby attended that party, as did Caserio, New England's director of player personnel since 2008. Easterby and Caserio are represented by the same agent, Bob LaMonte.
The Texans have requested permission to interview Caserio for their GM job but have not been granted permission to date, sources said.
The NFL's anti-tampering policy states, "Any interference by a member club with the employer-employee relationship of another club or any attempt by a club to impermissibly induce a person to seek employment with that club or with the NFL" is impermissible.