It was the night before federal prosecutors would reveal explosive bribery charges against Senator Robert Menendez, and his adult children appeared unaware of the news storm that was about to hit the family.

Alicia and Rob Menendez seemed to be in great spirits at a glitzy political gala celebrating a new generation of Latino leaders.

Ms. Menendez, an increasingly high-profile anchor on the cable news network MSNBC, stood before a room filled with Latino politicians, media executives and entertainment figures, as the emcee of the annual Congressional Hispanic Caucus Institute party in Washington.

Among those in attendance was her brother, a Democratic congressman from New Jersey who is in his first term representing a majority Hispanic district, a seat once held by his father.

In her opening remarks that evening last fall, Ms. Menendez exuded confidence, poise and glamour. The event was a triumph for the Menendezes, who hammed it up in selfies that Ms. Menendez shared the following morning.

“So fun to host @chcidc’s 46th Annual Awards Gala,” she wrote on Instagram. “Sibling time was a bonus.”