Joel Perkins thought he was doing the safe thing when he decided to transport his grandmother’s ashes by car from northern Washington to San Diego rather than risk sending them by mail.

On Tuesday night, it became clear that he was wrong, when someone broke into his car in the Mission District and stole his bike and a box containing his grandmother’s ashes — the second such crime in about a month in San Francisco.

Perkins, 23, and his family needed to move the remains and couldn’t fly with them, because they no longer had a certificate of death or cremation.

“My grandpa said, ‘I don’t really feel comfortable mailing my deceased wife across the nation.’ So the only avenue left was for me to drive them down, and I was pretty happy to do it,” Perkins said.

The theft occurred almost exactly a month since ashes of another family’s relative were stolen from a rental car parked near Fisherman’s Wharf.

Perkins said that until recently, the remains of his grandmother, Sophie Perkins, had rested under a plaque beneath towering trees on a remote and verdant piece of land in Spokane, Wash.

Perkins’ grandfather, who is raising two grandchildren, needed to sell the land, making it necessary to move the ashes.

That’s how Perkins found himself at the memorial for his grandmother two weeks ago. When he arrived, he was startled to learn it was her birthday.

“I was so young when she died — the more minute details of her life were lost to me,” he said.

In Perkins’ clearest memory of his grandmother, they’re drinking tea and eating strawberries in her kitchen in San Diego. He buried a teapot under the tree where the memorial had been.

On the drive south with his grandmother’s remains, Perkins stopped in San Francisco to visit a friend at Mission and 14th streets, leaving his bike in the car.

When he left his friend’s building and discovered the break-in, it was obvious his bike had been stolen. It was only after he began vacuuming glass off the floor that he noticed the ashes, too, were missing.

For Perkins, the theft brought back the feeling of his grandmother being taken away from him when she died of cancer 20 years ago.

He filed a police report and spent days combing the streets around the site of the theft, buying cigarettes to offer people on the street to start conversations and following a trail of tips through the city’s seedier underbelly, looking for traces of his bicycle in the hope that it might lead to the ashes.

“I went to all these different dead-end alleys, some of them kind of scary places, talking to all kinds of people, giving away cigarettes to see if I can start a conversation, feeling driven to go out there on this false maniacal hope that I might find her,” he said.

He has tried to comfort himself with the thought that maybe this is his grandmother’s way of making a break for freedom. He still holds out hope that the remains will be found.

“I almost start crying thinking about (what it would be like) if somebody turned them in,” he said. “That would just be a miracle.”

Filipa Ioannou is a San Francisco Chronicle staff writer. Email: fioannou@sfchronicle.com Twitter: @obioannoukenobi