The shooting of the polarizing former police chief of Ciudad Juarez has brought back bad memories of the border city's years of bloody drug-related violence and government abuses.

Former chief Julian Leyzaola was shot twice, including once in the head, in an incident near the border with El Paso, Texas, on May 8. He survived the incident but was still recovering this week at a military hospital in Mexico City.

Conflicting versions have circulated over what led to the shooting. Authorities on Tuesday said they will be investigating Leyzaola for an allegation of sexual assault that might have sparked the attack as an act of vengeance.

The former Juarez chief is not a small-time cop. He built an almost larger-than-life profile, gaining enthusiastic supporters and equally passionate detractors, for employing tough tactics against drug cartels in the cities of Tijuana and Juarez.

Leyzaola rose through the ranks of Mexico's military before taking over security duties in Tijuana, Baja California, piling up significant arrests and drug busts but also collecting accusations of torture and abuse of authority.

His successes in Tijuana nonetheless propelled Leyzaola to police chief in Ciudad Juarez, right as the city was called the world's most violent. He held the position between 2010 and 2013.

According to authorities, Leyzaola was attacked while sitting in his vehicle as he waited for his wife to exchange currency before their plans to head to El Paso. Moments later, the Chihuahua state prosecutor's office said two men were detained while attempting to flee the scene.

Footage released of the incident shows a gunman approach Leyzaola's vehicle and shooting at the driver's side.

Suspect Jesus Castañeda Alvarez, told authorities he shot Leyzaola because Leyzaola had attempted to assault his sister while he was still police chief.

"Leyzaola abused and tried to rape my sister, that's why I did it," Castañeda told authorities.

Leyzaola later broke his silence, telling the investigative weekly Zeta that the current operations director of the Juarez police, Jesus Antonio Reyes, order the attack against him. Leyzaola claimed the gunman told him just before he fired: "Message from director Reyes."

Chihuahua's prosecutor on Tuesday ordered an investigation into the rape accusations against the former chief of police, and also advised Leyzaola to file charges against Reyes, for his alleged implication in the attack.

Leyzaola was involved in 2012 in a shootout with federal police forces in Ciudad Juarez who had mistaken his convoy for one of a narco group. He's survived assassination attempts and faced numerous death threats.

Since leaving his post in Juarez, Leyzaola formed a private security company, Titan SA de CV, one of few security companies in the border city that are permitted by Mexico's army to carry heavy firearms.

He's made no other comments since the shooting.