Gang experts say the tattoos on Kilmar Abrego Garcia’s knuckles are unlikely to signify gang membership. The president says otherwise.

President Trump has claimed that Kilmar Abrego Garcia, the man mistakenly deported to El Salvador in March, is a member of MS-13, the Salvadoran-American criminal gang, and that the tattoos on Mr. Abrego Garcia’s knuckles prove it.

In a post nearly three weeks ago on Truth Social, Mr. Trump’s social media platform, he gave his version of a primer on those tattoos, showing a photo of Mr. Abrego Garcia’s hand, with one small tattoo on each finger: a marijuana leaf, a smiley face with X’s for eyes, a cross and a skull.

Above each of those black tattoos was a letter or a number — M, S, 1 and 3 — in a sans-serif font that clearly had been superimposed onto the photo. “He’s got MS-13 tattooed onto his knuckles,” the president wrote in his post.

In other photos, however, including ones shared by Mr. Abrego Garcia’s wife, Jennifer Vasquez Sura, the letters and numbers do not appear on Mr. Abrego Garcia’s knuckles.

Here’s a close-up view of Mr. Abrego Garcia’s tattoos from one of those photos:

Each of the tattoos on Mr. Abrego Garcia’s knuckles is extremely common, but even combined, they are unremarkable, several tattoo experts said.

And according to experts on gang membership, the tattoos that usually signify MS-13 membership are often much clearer in their association with the gang. Many times, they actually say MS-13, those experts said.

“I can tell you, MS-13 does not equivocate; they don’t leave any ambiguity when it comes to their tattoos,” said Jorja Leap, an anthropologist at the University of California, Los Angeles, who has been working with and studying MS-13 members for more than two decades.

Mr. Abrego Garcia’s tattoos leave room for interpretation, Ms. Leap said, which does not align with the bold way MS-13 operates. The gang, she said, is proud of the reputation that it is violent and lethal, and members often showcase their association through their tattoos.

Sometimes, Ms. Leap said, the gang’s full name, Mara Salvatrucha, is tattooed in large letters on the chests of its members, or featured across their backs and down their arms. It also is not uncommon for the gang’s members to have MS-13 tattooed onto their cheeks and necks, she said, or to have tattoos of a devil-horns hand gesture — index and pinkie fingers up, everything else closed in a fist — because it’s the gang’s symbol.

“They are very clear, again, about their brand, and they espouse pride in it,” she said.

José Miguel Cruz, an expert in transnational gangs who has interviewed more than 2,000 members of Central American gangs, including members of MS-13, said nothing about Mr. Abrego Garcia’s tattoos signals MS-13 membership.

Mr. Cruz has seen MS-13 members with many versions of elaborate tattoos: full-face ones of MS-13 and also ones like 666 or a beast that represents Satan. But he said he has never seen the combination of tattoos that are on Mr. Abrego Garcia’s knuckles.

“The basic message here is that we cannot infer that he’s MS-13 just because of those tattoos,” said Mr. Cruz, an associate professor in the Department of Criminology and Criminal Justice at Florida International University.

Paul Bradley, the owner of Titan Ink, a tattoo shop in suburban Washington, where Mr. Abrego Garcia lived, has worked as a tattoo artist for 20 years. Referring to the tattoos on Mr. Abrego Garcia’s knuckles, he said he has tattooed each of those images on people countless times.

“I’ve pretty much done those tattoos on almost every spectrum of person: man, woman, young, old,” Mr. Bradley said. They are “just symbols that people like for one reason or another.”

Mr. Abrego Garcia’s tattoos helped his wife, Ms. Vasquez Sura, to recognize him in photos posted online of men at a prison in El Salvador, where migrants were sent after being deported from the United States.

Since Mr. Abrego Garcia’s deportation, the Supreme Court has ordered the Trump administration to facilitate his release. The president has dug in, calling him a dangerous gang member who should not be let back into the United States.

Law enforcement officials say the tattoos on Mr. Abrego Garcia’s hands do not qualify as singular and definitive evidence of membership in MS-13. While many police departments consider tattoos when trying to determine whether someone is a member of a gang, they also weigh other factors, including the use of hand signs or symbols linked to gangs and known association with gang members.

David C. Pyrooz, a professor of sociology at the University of Colorado Boulder and an expert on gangs and criminal networks, said even a blatant MS-13 tattoo on someone’s neck or face would not guarantee active gang membership because that membership doesn’t last forever and tattoos are hard to remove. It might have been a tattoo that they had inked 10-15 years ago, long before they dropped out of a gang to get a job or start a family, as many gang members do, he said.