Thousands of mothers of missing Mexicans are marching in cities across the country to mark Mexico's Mothers' Day and demand authorities find their children — or at least their bodies.

Some 40,000 people have disappeared since the start of the country's drug war in 2006. Very few have ever been found, though clandestine mass graves dot the countryside. Often, human remains are not identified, leaving some families to undertake their own investigations.

Rocío Morales' son, Pedro Morales González, was kidnapped almost 11 years ago. She wept desperately Friday in Mexico City as she held up a banner that she has been marching with for years.

Mothers in Veracruz and the northern city of Ciudad Victoria also marched, chanting "They took them alive, we want them back alive!"