Federal prosecutors have subpoenaed records from the head of the Port Authority according to The Wall Street Journal — a request that apparently expands the scope of the investigations surrounding the behavior of the agency and the office of New Jersey Gov. Chris Christie.

By this point, the cast of characters in the Christie scandal has grown large enough that a quick who's who is in order. The Port Authority is the two-state agency that manages the bridges and tunnels that connect New York and New Jersey, as well as the World Trade Center site. The chairman of the agency is David Samson, the target of these new subpoenas. The executive director of the Port Authority on the other hand is Patrick Foye, who was the person that demanded the "traffic study" that closed several lanes leading onto the George Washington Bridge last September be terminated. That closure apparently came at the request of a senior Christie staffer, in an email issued to a Christie appointee suggesting it was "time for traffic problems in Fort Lee" — the Jersey town at the base of the George Washington Bridge that the lane closures ensnared in traffic jams for a full week. Got it?

Samson was a Christie appointee, nominated in 2010 for the position despite "questions of conflict" as the Journal reported at the time. Samson, you see, is a lawyer with the firm Wolff & Samson, which has represented a number of real estate clients, including Larry Silverstein, the developer of the World Trade Center site. In January, The New York Times speculated that Samson was likely to be a target of investigation since he was "regularly consulted by the political operatives at the port who conceived and carried out the shutdown." At that point, Christie assured the public that Samson wasn't involved in the closures.

In addition to the World Trade Center site, Silverstein also bid on the development project known as "Hudson Lights," located immediately adjacent to the George Washington Bridge on-ramps in Fort Lee. Earlier this year, MSNBC's Steve Kornacki speculated that project might have been involved in the decision to close the traffic lanes. Sokolich mentioned the effects on the project in September emails to former Jersey Port Authority executive Bill Baroni — a Christie appointee who has since resigned. What's more, as the Journal reported on Monday: "New Jersey prosecutors are also looking into allegations by the Democratic mayor of Hoboken, N.J., that the Christie administration threatened to withhold federal money if she didn't approve a real-estate development for a Wolff & Samson client."

Last June, the Bergen Record reported on Samson's lengthy list of recusals from decision-making at the agency, given his history of working with developers. The Record describes one such recusal:

Samson recused himself from the vote on Atlantic City, records show. But he answered reporters’ questions about the deal after the meeting, saying at one point, “We are hoping that this will be an opportunity to retain those natural customers for the Atlantic City Airport area. The opportunity for expansion is significant."

The new subpoenas expand the investigation in two ways. First, they demonstrate that federal officials in New York are investigating what happened with the Port Authority and the closures. And, second, they reinforce that Samson's considered likely to be a crucial player in figuring out the answer to that question.