Nancy Grace, host of Fox Nation's "Crime Stories," argued authorities overlooked key evidence that could have led to an earlier arrest of the Gilgo Beach serial killings suspect. On "America Reports" Monday, Grace explained that a witness' description of suspect Rex Heuermann's stature and vehicle made him "easily identifiable" to authorities.

WATCH GRIM TIDE: HUNTING THE LONG ISLAND SERIAL KILLER

NANCY GRACE: Many, many red flags were missed. I call it evidence. A witness saw Amber Costello, one of the original victims, with a guy that matches Heuermann's description. He's very easily identifiable, about 6'4", about 240-50 pounds. And his Chevy Avalanche, which I'd like to point out, discontinue manufacture 2013. So who else is going to have a Chevy Avalanche with one of the victims about 20 minutes away from the disposal sites of the body? He parks it right out front. Hello?

New York prosecutors said Monday they were "pleased" Heuermann appeared surprised by his arrest in connection to the gruesome Long Island slayings after authorities accelerated the case to maintain secrecy.

Suffolk County District Attorney Ray Tierney said he believes Heuermann did not expect to be taken into custody in Manhattan last week despite allegedly closely monitoring the investigation on the internet.

"I think he was extremely surprised," Tierney told "America's Newsroom" Monday. "I think we utilized the grand jury because we wanted to maintain investigative secrecy. We were concerned about that all along."

The 59-year-old married father of two allegedly killed three of the four women known as the "Gilgo Four" in 2010, and he's the prime suspect in the fourth woman's death.

Fox News' Bailee Hill contributed to this report.