Police arrested two women Saturday for allegedly holding an American retiree captive in his Tijuana home and forcing him to write them checks.

Police went to the home after receiving an anonymous tip that Richard Mattson was being held captive there, police spokesman Ernesto Alvaro said. Officers found Mattson inside and arrested the two women.

Alvaro said the women held Mattson, 65, captive for four days and forced him to write checks for them. They were found with drugs and a check for 1,500 pesos ($113) signed by Mattson, Alvaro said.

The spokesman could not immediately say how the women kept Mattson from leaving his apartment.

Mattson, of Tacoma, Washington, said the women stole more than $4,000 from him. He declined to say how he met the women, whom police described as sex workers.

"These women gave me a very hard time. They held me captive and stole more than $4,000 from me," Mattson told The Associated Press at the police station.

One of the women, Candelaria Ortiz, denied kidnapping Mattson.

"We did not hold him captive. He came and went whenever he wanted. He had his own keys. How can he say he was captive?" Ortiz told AP from inside a police car parked outside the station.

Mexico has one of the world's highest kidnapping rates. The Mexican government says about 97 kidnappings are reported each month but acknowledges most abductions go unreported because of fear that police themselves may be involved.

The nonprofit Citizens' Institute for Crime Studies estimates the real rate is closer to 500 a month.

Mattson, who moved to Tijuana eight months ago, said he wants to stay in Mexico.

"Life here cost me a third of what it would in the United States. Beside, I really like it, even after this experience," he said.