"Here is an officer who did a dangerous, risky job, has done it well, and the government has brought these charges against him because he didn't admit to having sexual intercourse with a woman," the lawyer said. "Somehow that's a federal crime?"
To hear prosecutors tell it, the relationship Fontan struck up with Sanchez after they met outside a courtroom in 2003 was particularly star-crossed.
Not only was he an undercover narcotics officer and she an accused drug user, she had an ex - in this case, Jose Sanchez, a Kensington cocaine dealer Fontan was later involved in investigating. Jose and Elizabeth shared a common last name but were not married.
Fontan warned her to keep her distance, and she read between the lines, said Assistant U.S. Attorney Neuman Leverett. He told jurors Tuesday that Elizabeth Sanchez later warned her former boyfriend about the law enforcement trap her new beau was involved in preparing.
That lapse came to a head in January 2008 during a cocaine drug buy the U.S. Drug Enforcement Administration set up with Jose Sanchez. Fontan, operating undercover, went to buy the drugs but the cocaine dealer never showed.
FBI agents became involved once the DEA began to suspect a leak within its investigation. It did not take long to zero in on Fontan.
Despite repeated questioning, the officer denied any relationship with Elizabeth Sanchez beyond that of a narcotics officer and an informant.
Fontan "was asked - trusted - to be an undercover officer in this investigation," Leverett said. "He knew who Jose Sanchez was, but he didn't tell anyone."
McMahon said Tuesday his client lied for a simple reason: He wanted to tell his wife about his affair first. She stood by his side Tuesday as he faced his day in court.
As for the investigation he allegedly derailed, Fontan's ties to Elizabeth Sanchez appeared to have had minimal effect, McMahon said.
Jose Sanchez was eventually charged, pleaded guilty to cocaine distribution charges, and is serving a 10-year prison term.
Fontan could soon join him. The seven-year police veteran has already lost his job. If convicted on the three counts of lying to investigators lodged against him, he could face up to five years in prison for each.
His trial was expected to resume Wednesday.