Mexico City, Mexico | Two items stand out in Donovan Alvarado's lost and found office at the end of a cavernous corridor of Mexico City's metro system: Urns containing the ashes of a child and of a young man.

Alvarado, 40, is the guardian of the only missing objects office of a subway system with 195 stations and 5.5 million daily users, some of whom are a forgetful bunch.

The 2,000 items that are lost each year end up in the badly-lit room at the end of Candelaria station, which is filled with identification cards, backpacks, bicycles, cellphones, toys, strollers, clothes and a mountain of shoes.

The phones in Alvarado's dusty office date from the 1980s, but the old surroundings don't keep him down. He has worked here for six years and has headed the lost and found department for more than a year.

"The satisfaction that we get from returning an object to its owner is priceless," Alvarado says. "The thanks people give with tears in their eyes doesn't have a price. This is such a noble office."

- Rebeca and Gustavo -Wearing a white shirt, a bright orange tie and a navy blue suit jacket with the metro's orange logo, the tall metro worker keeps the two most important items of all at the top of a metal shelf.

The two urns were found in metro cars between December and January. While the law requires that lost objects be donated if nobody claims them after six months, Alvarado is holding on to those two until he finds the owners.

The varnished, dark wood urn has a small plaque with the name Rebeca Menes Perez, who was born on September 14, 2010, and died on March 8, 2014.

The child's urn is decorated with two red heart-shaped stickers with white dots flanking a metal angel whose wings are spread wide.

The plaque on the second and bigger wooden urn indicates that the ashes are those of Gustavo Guerra Orduna, who was born in 1973 and died in 2000.

Alvarado has placed an image of Jesus Christ behind the urns "for their souls to rest in peace."

There are two other urns on the shelf, but they are empty, which leads him to believe "they were never used to store ashes."

A former reporter and media department employee for the city government, Alvarado and his two coworkers have gone through phone books to look for the urns' owners.

When Alvarado thought he was close to finding the people who left behind the ashes of Gustavo and Rebeca, he went to the civil registry to get more information, but officials refused due to privacy laws.

- Grateful, tearful eyes -The urns are not his only mission. He still hopes to find the owner of a US passport filled with stamps from border agents, or the couple who left a large photo of their wedding in a train.

But he also recalls a few successes, like the day a man forgot a medical report showing that he had a brain tumor and needed an urgent operation.

"There was a hospitalization order, so I looked for him. The gentleman lived in Baja California Norte (state in northwestern Mexico) and after several phone calls, I found one of his relatives, who told him that his report was here," Alvarado recalls.

"The gentleman came and, with tears in his eyes, blessed me 20,000 times," he says.

As for the urns, his quest continues and he will keep them "as long as necessary." 

"I would like to return them to their families. I won't give up," he says.

Based on the dates on the urns, Alvarado thinks the owners were taking the urns from a cemetery niche to a house and that they forgot them "because of the pain" of having the remains in their hands again.

During his own 90-minute commute in the metro each day, Alvarado "meticulously" looks around to make sure that "nobody forgets anything, because you never know what they can forget."