El Paso police are investigating threatening graffiti on billboards alongside mannequins hanging from nooses in messages reminiscent of threats issued by drug cartels in Mexico.

The El Paso Times reports that motorists alerted police to the graffiti Thursday. Billboard companies said the messages were vandalism, not paid advertisements, and removed them.

One message said "Silver or lead" in Spanish, a threat that in Mexico means "Pay up or get shot." The other said "Dying for drugs."

El Paso Police spokesman Sgt. Chris Mears said he had never seen anything like it in El Paso, which is on the border with Mexico.

Drug cartels often hang banners in Mexican cities with graphic threats and sometimes hang victims from overpasses. Such public threats are virtually unheard of on the U.S. side.