Jafari, the National Zoo giraffe who was operated on Oct. 5 for skin cancer, took a turn for the worse yesterday and was euthanized, the zoo said.

Veterinarians had not been optimistic after the operation. The tumor had spread from flesh to bone and could not be completely removed.

Jafari had been closely observed since his surgery and yesterday appeared disoriented and began walking in circles, zoo spokesman John Gibbons said.

"Due to the poor prognosis, Zoo veterinarians and animal-care staff decided to euthanize," the zoo said in a statement.

The zoo grounds were closed two hours early so the animal could be given a lethal injection in the outdoor yard at the Elephant House, where he lived.

"It was a very sad day," Gibbons said.

Jafari, who stood about 13 feet tall with a neck that accounted for about half of that, would have been 3 in December. He was born at the Bronx Zoo in New York and brought to Washington in April 2004.

In late August, zoo staff first noticed the lump on the top of his head. Veterinarians drew fluid on two occasions. The second indicated the presence of cancer cells. At the time of the operation, the tumor was described as about the size of a grapefruit.

Jafari was treated for several weeks for complications associated with skin cancer, the zoo said.

Saturday was the last time Jafari was on exhibit, Gibbons said.

He said that watching the giraffe closely was the best way to determine how he was faring. Gibbons said yesterday that "it was pretty obvious" that it was time to end Jafari's life.

Gibbons said that at 5 p.m. yesterday, zoo police began asking visitors to leave so they could close the grounds at 6 p.m. Normally, buildings close at 6 and the grounds at 8 p.m.

After the procedure, the giraffe's 1,300-pound body was taken by truck to the zoo's pathology lab for examination, Gibbons said.

At first it was reported that the tumor on the back of Jafari's head was basal cell carcinoma. Yesterday, Gibbons said specialists were not certain whether it was basal cell carcinoma or melanoma. In either case, he said, it was unusual because neither of the skin cancers had been diagnosed in giraffes.

Noting this, Gibbons said that Jafari's death provided an opportunity to learn about the disease in giraffes.

The zoo is left with one giraffe, a 3-year-old male named Randall.