An attorney for a New York man identified as a person of interest in the death of a baby found buried in his backyard said Monday his client invoked his constitutional rights in declining to speak with investigators.

Robert Rodriguez, a 30-year-old salesman for an appliance retailer, was on Long Island but would not be returning to the Farmingdale home where the baby's remains were found Saturday, his attorney Byron Divins told The Associated Press in a telephone interview.

"I wouldn't say he refused to cooperate. I'd say he is standing on his constitutional rights," Divins said.

Rodriguez shared the home with his girlfriend, Heather Kowalczik. Neither he nor Kowalczik has been charged in the investigation.

State police announced on Saturday they had discovered the remains of a baby buried in the backyard of the two-family home. They said information provided by Kowalczik led them to the discovery.

Circumstances of the child's death were not immediately revealed, and authorities did not confirm the identity of the buried child pending a forensic examination. Police said Kowalczik told them her 17-month-old son, Justin, died in the summer of 2010.

The couple has two older children, ages 6 and 9, but police said Rodriguez is not the father of the baby presumed buried in the backyard. The two children are in the custody of county child welfare authorities.

State Police Major Patrick Regan said at a briefing Saturday that the death is considered suspicious. "We don't have a cause of death, and to our knowledge, there was never a report made of the child being missing," he said.

A trooper at the Farmingdale barracks said Monday the results of the examination could take several days.

Dr. Michael Baden, who retired in 2011 as the chief forensic pathologist for the state police and served as chief medical examiner in New York City, said determining a cause of death would depend largely on the condition of the body and the degree of decomposition.

He said if the body was buried in plastic or other protective covering, investigators would likely have a better chance of determining how the person died. He said strangulation is the most common cause of death in murders involving young children.

State police did not disclose any details on the child's condition in the Farmingdale investigation.

Kowalczik's whereabouts Monday were not immediately known, although published reports indicated she has relatives in Orange County in upstate New York. Kowalczik and Rodriguez reportedly lived in Orange County before moving to Long Island about two years ago.

The police investigation began after workers from Suffolk County's Child Protective Services agency went to the home Saturday to check on the children. They grew concerned when the family couldn't account for the whereabouts of a child born in 2009.

Kowalczik told them the child had died shortly after the family moved to Farmingdale from Orange County two years ago, Regan said.

Michelle Monaghan, a neighbor of the couple on a quiet suburban street, said her 5-year-old daughter had played with Kowalczik's children this summer in the backyard where the body was found.

"Nobody knows about a third child; we know nothing," Monaghan told reporters Monday. "I'm very disturbed that my daughter has played next door knowing there was a little one..."

She said she was at a loss to determine what might have happened: "You don't know what people are enduring behind closed doors."