Neither Mr. Murdock nor Ms. Greco could be reached on Tuesday, and a lawyer for Mr. Murdock did not return a call seeking comment.
The dog, an 8-month-old female named Rain who weighs about 60 pounds, was at Animal Care Center of NYC’s shelter in Brooklyn on Tuesday, a spokeswoman said. Ms. Greco was expected to retrieve the dog on Wednesday, officials said.
It was not the first time a panicky passenger has pulled such a maneuver at a New York-area airport, but neither Delta, the F.A.A. nor the Port Authority, which operates La Guardia, could say on Monday just how unusual it was for someone to make such an escape.
“This doesn’t happen every day at the airport,” Ms. Valens said.
Mr. Plummer said he had noticed Mr. Murdock standing after the plane left the gate. “They seemed really nice,” Mr. Plummer said of the couple.
Mr. Murdock told a flight attendant that he could not sit down because of his post-traumatic stress disorder, Mr. Plummer said.
“If I sit down, I’ll freak out,” Mr. Murdock said, according to Mr. Plummer.
The flight attendant again asked Mr. Murdock to take his seat, and again he refused, Mr. Plummer said. Instead, he began to walk toward the front of the plane, getting far enough that Mr. Plummer lost sight of him.
According to the complaint, a flight attendant had noticed Mr. Murdock and Ms. Greco walking through the plane, and had heard Mr. Murdock say, “I need to get off the plane.” She also heard him say that he was going to “pop the door” and that he would “spazz out” if he did not get off.