A man suspected of participating in the rapes and killings of at least 10 women in a border city made infamous by the deaths of more than 100 young women since 1993 has been arrested, U.S. officials said Thursday.

U.S. Ambassador Tony Garza called Tuesday's arrest of Edgar Alvarez Cruz on immigration violations in Denver "a major break" in the investigation into the unsolved deaths in Ciudad Juarez, across from El Paso, Texas.

"We believe Alvarez Cruz's arrest will help U.S. and Mexican law enforcement authorities solve numerous cases involving the murders and disappearances of women in Ciudad Juarez and in Chihuahua, and ultimately bring their killers to justice," Garza said.

Tim Counts, a regional spokesman with U.S. Immigration and Customs, said Alvarez Cruz was in its custody but declined further comment, citing security concerns. Federal officials in Denver did not have any information on where he was being held.

Garza said the U.S. Marshals Service was assisting Mexican authorities with the investigations into the killings of the women in Ciudad Juarez and other parts of the border state of Chihuahua.

Most of the victims were dumped in the desert outside of Ciudad Juarez, provoking outrage that reached around the world. Many of the victims were young women last seen in the city's downtown or after taking buses. Their bodies often didn't appear until months later.

Mexico Attorney General Daniel Cabeza de Vaca told reporters Alvarez Cruz had been under investigation but fled the country.

"We don't exactly how many homicides he may have been responsible for, but there is solid evidence in several cases we know of," Cabeza de Vaca said.

He said federal authorities were in contact with prosecutors in the northern state of Chihuahua, where Ciudad Juarez is located, to learn more about the suspect.

The U.S. Embassy said Alvarez Cruz may had been involved in 10 killings as part of a gang.

There have been prosecutions in connection with some of the dozens of killings, but family members of some victims say authorities have to bring the true culprits to justice.

Police have arrested several people, including an Egyptian chemist who died in prison last month; a bus driver whose conviction was overturned and his co-defendant, who died in prison before sentencing. A group of gang members are serving out sentences related to some of the murders.

Federal authorities intervened in 2003, promising to solve the rape-strangulation cases of 14 teenagers and women in Juarez. But the office of attorney general quietly closed those investigations recently, without getting to the bottom of what happened.