The 911 caller said he "murdered his uncle's wife," and when police arrived at the Arlington home Friday, they found her decapitated body in the basement, according to court documents.

Matthew J. Pahno, 21, told the 911 operator where to find her, and police found her severed head in a washbasin near her body, according to the affidavit for a search warrant.

Pahno, of South Carolina, was charged with first-degree murder in the slaying of Maria Teresa Dela Cruz Escoto, 40, police said. They declined to comment on a motive for the slaying.

Pahno was ordered held without bond at Arlington County's detention center.

Escoto's body was found shortly before 2 p.m. Friday in the 3600 block of Vacation Lane in the Cherrydale section of North Arlington. When police arrived, they cordoned off the block.

A man identified by neighbors as Escoto's father-in-law emerged from the house and was immediately taken into protective custody, according to the affidavit filed in Arlington Circuit Court this week. Pahno exited the house in bloodied clothing, the affidavit said.

Neighbors described Escoto as a friendly, earnest woman who married into the Pahno family last year.

When Escoto was killed, her husband, Nick Pahno, was visiting his mother in Greece, neighbors said.

"It is terrible beyond words, and what happened breaks our hearts," said a neighbor, who said he is close to the family but who declined to provide his name because he did not have permission to speak on its behalf. "It's a shame when anyone is killed, but especially her."

Escoto's husband could not be reached yesterday. Except for a marked Arlington police car parked on the street in front of the red brick house, there was no other evidence that a slaying had recently occurred on the quiet, tree-lined block.

According to the affidavit, Pahno identified himself by name to the 911 operator and was advised to wait at the home until police arrived. When they got there several minutes later, the police drew their guns and commanded that anyone inside come out with hands up, neighbors said.

In the affidavit, a detective wrote that investigators wanted to search the home for a weapon, writings, cell phones and computers, as well as any documentation that would illustrate a history of mental illness, treatments or medications involving Pahno. It was not known yesterday whether any such items were found in the home.

The slaying of Escoto is the third in Arlington this year, two more than all of last year. In 2004, according to department statistics, overall violent crime fell about 6 percent, to its lowest level since 1962.

Matthew Pahno, 21, told police where to find relative's body.