Crime Scene

The Science of the Search for the Boy on the Milk Carton

By MICHAEL WILSON

Published: April 20, 2012

Upon the discovery of buried human remains, forensic archaeologists and anthropologists typically keep digging in a circle around them, in effect creating, beneath the bones, an elevated section of dirt. A pedestal as described by Geberth.

Etan Patz disappeared on the streets of SoHo in 1979. His picture with its bowl haircut and toothy grin was seen all over the country; children his age grew up with Etan staring back at them from the milk carton on the breakfast table. Thirty-three years later, investigators believe strongly enough in new leads in the case to have blocked off the area around an apartment building at 127B Prince Street to dig up the basement in search of his remains.

The search is an extraordinary show of manpower in the case, a barrage of tents and police trucks on the swank streets of SoHo. In 1979, the basement was the workshop for a handyman from the nearby building where Etan lived. Three decades have radically changed the streets above, with high-end jeans stores and moneyed tourists replacing the textured knit of 1970s SoHo. But what lies beneath is unchanged.

“They may come upon a historical site,” said Vernon J. Geberth, a retired New York City police lieutenant commander who wrote a procedural bible, “Practical Homicide Investigation.” “When you start digging in Lower Manhattan, you don’t know what you’re going to find.”

In this case, the discovery could be gruesome, especially when one considers pictures of the sunny little boy who vanished that day. But this is a simple fact of detective work; the means themselves are not for the squeamish.

The concrete floor is now being broken open by jackhammers. The police have said a cadaver-sniffing dog recently taken there alerted investigators to the presence of cadaverine, the foul-smelling gas produced by decomposition. Some experts, including Dr. Michael Baden, the city’s chief medical examiner when the boy disappeared, warned against reading too much into the dog’s reaction. “Very unlikely,” he said, that gas produced by a body buried 33 years would still be detectable. But Mr. Geberth said the concrete might have served to cap the gas, preserving it.

The basement is 62 feet long, 13 feet wide.

“That’s a big area,” Mr. Geberth said, with no obvious starting point to dig. “You’re not going to have the telltale signs of any recent disturbance.” To narrow the search, ground-penetrating radar equipment is typically used to identify a cavity underground.

“A body would decompose and cause a defect in the earth,” Mr. Geberth said. “That area would be cordoned off. You’d begin digging with trowels, like an archaeological dig.”

The scene would be meticulously mapped and marked with grids and stakes to measure the depth of any evidence recovered.

What may have survived after all these years and the effects of the moisture of the soil and the bacteria from decomposition?

“There probably would still be bone,” Dr. Bader said. “The permanent teeth that we have, more so than baby teeth, last for decades. Longer than that. It’s easy to get DNA from teeth and long bones.”

Squint and look at those teeth from the milk carton. “The eruption of teeth in the human body is a relatively predictable process during the early years of growth,” according to “Practical Homicide Investigation.” “The loss of these baby teeth and the eruption of the first permanent molars begins at approximately 5 years of age.”

Etan was 6.

There could still be hair. “That definitely would provide DNA,” Dr. Baden said. Any blood spilled would have long decomposed, he said, but investigators will surely be looking for signs of insect activity.

“Maggots can have the DNA of an individual,” from feeding on a body, Dr. Baden said. The pupae cases left behind from hatching flies could contain the body’s DNA, he said.

Any DNA found could be compared to that of one or both of Etan’s parents to determine a match.

Etan was last seen wearing white sneakers and a pilot’s cap. Most articles of clothing would have been lost to time. “Certain clothing will last longer than others,” Dr. Baden said. “Plastic can last a long time, suspenders or something. Nylon.”

Mr. Geberth said the stark statistics surrounding the murder of children offer some hope that Etan’s body was disposed of intact.

“These guys want to get rid of the body as soon as possible,” he said of child killers. “They want to distance themselves from the body.” Burial would be an attractive choice, and not that difficult, he said. “A hell of a lot easier than burying an adult.”

Where there was a child’s body in 1979, there almost surely is a telltale pocket of space today. “It’s going to leave a smaller cavity,” he said, “but there’ll still be a cavity.”

Find that, and you find the boy, waiting, after all this time, for a pedestal.