By TIM WEINER
 
MEXICO CITY, Feb. 19 — The former chief of Mexico's secret police, Miguel Nazar Haro, was arrested here on charges of kidnapping a leftist leader 29 years ago, federal officials said Thursday.

He is the first former government official arrested in connection with crimes committed during Mexico's "dirty war" against the left, which lasted from the 1960's to the 1980's. Hundreds of suspected enemies of the government were arrested, tortured and killed by state agents.

Mr. Nazar Haro, 79, was an officer in the Federal Security Directorate, which served as an intelligence service and a secret police force. He led the directorate from 1978 to 1982; it was disbanded in 1985.

He was an important liaison for the C.I.A. during the 1970's and early 1980's, providing the United States with information on leftists throughout Mexico, Central America and the Caribbean, American officials say.

The C.I.A. blocked his indictment by a federal grand jury in San Diego in 1982, immediately after he left his post as chief of the secret police. He was suspected of involvement in an auto-theft ring that stole hundreds of cars in California and brought them to Mexico, according to the chief federal prosecutor in San Diego at the time.

The prosecutor, William H. Kennedy, asserted then that C.I.A. officials had told him that Mr. Nazar Haro was their most important source in Mexico and Central America. The Federal Security Directorate gathered information used by the Reagan administration to justify assertions of Soviet and Cuban subversion in the region.

The C.I.A. argued successfully that the importance of the information gleaned from Mexico's secret police overrode the interests of United States law enforcement.

The arrest of Mr. Nazar Haro on Wednesday night on a Mexico City freeway was the first concrete achievement by a special prosecutor appointed by President Vicente Fox to investigate crimes committed during the war against leftists.

Mr. Nazar Haro's predecessor as chief of the secret police, Luis de la Barreda Moreno, faces similar charges and remains a fugitive.

Mr. Nazar Haro is charged in the disappearance of Jesús Piedra Ibarra, a leftist leader who was arrested in 1975, beaten, tortured, transported to a military camp in Mexico City, and held in secret for years, according to Mexico's human rights commission. He was last reported alive in 1984. His body has never been found.

He led a small band of armed guerrillas called the 23rd of September League, a tiny part of a much broader left-wing movement in Mexico. His mother, Rosario Ibarra, is a prominent advocate for the arrest of government leaders of the era, including Luis Echevarría, who was president from 1970 to 1976.

"A single arrest doesn't mean much," she said on Thursday. "The orders came directly from Luis Echeverría." Mr. Echeverría has been questioned by the special prosecutor but refused to testify.

The Supreme Court ruled in November that former officials could be prosecuted in disappearance cases, saying no statute of limitations could apply when no body had been found.