A Luxembourg performance artist arrested during Art Basel after spray-painting a glass window at the Miami Beach Convention Center has pleaded not guilty to a misdemeanor criminal mischief charge, according to newly filed court records.

Thomas Iser, 38, entered the plea on Monday and requested a jury trial in Miami-Dade County Court, according to filings obtained by Urgent Matter. His attorney also asked the court to waive Iser’s personal appearance at arraignment and pretrial conferences.

Iser was arrested on December 3, during the height of Miami Art Week, after police said he used a can of chalk-based marking spray to write the phrase “Sorry to disturb art in progress” on a glass window at the convention center. The damage was later estimated at $400, according to a Miami Beach Police arrest affidavit.

The incident drew international attention after Artnews reported that Iser was accompanied by his 3-year-old daughter at the time and described the act as a planned performance rather than vandalism.

"The gesture wasn’t accidental or improvised. I initiated the action and invited my daughter to express herself freely," Iser told Urgent Matter. "She then began drawing on the glass, without instruction on what to draw."

When asked what his daughter drew, Iser responded, "She drew little faces, I guess. I don't exactly know, but she did something," accompanied by the flexed biceps emoji.

Police said officers detained Iser after pedestrians alerted them to the writing on the glass. City workers were able to remove some of the markings at the scene, and police determined that no further crime-scene processing was necessary, according to the affidavit.

Iser was charged with misdemeanor criminal mischief involving damages of more than $200 but less than $1,000. He was released on a $500 surety bond and is not currently listed as being in custody. No court hearings have yet been scheduled.

He has since shared video of his performance and encounter with police on Instagram. In the video footage, police officers are seen holding his daughter as he’s detained.

Clarification published 8:00 a.m. December 16, 2025: An earlier version of this article described Iser's performance as "spontaneous," but Iser has said the performance was planned and not accidental or improvised.

Follow along with other art crime stories at Urgent Matter’s art crime tracker.

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