Earlier today, agents from the FBI searched the offices of uBiome, the medical testing company that sells analyses of an individual’s microbiome — the bacteria that live in the gut, according to a report in The Wall Street Journal.

The FBI is reportedly investigating uBiome’s billing practices, the WSJ reported.

“I can confirm that special agents from the FBI San Francisco Division are present at 360 Langton Street in San Francisco conducting court-authorized law enforcement activity. Due to the ongoing nature of the investigation, I cannot provide any additional details at this time,” a spokesperson for the FBI confirmed.

360 Langton street is listed as an address for uBiome. Numerous questions surrounding the clinical validity and efficacy of microbiome analysis remain, and uBiome could be under the microscope for the fact that it offers physician-ordered and consumer-requested test kits. “We are cooperating fully with federal authorities on this matter. We look forward to continuing to serve the needs of healthcare providers and patients,” a spokesperson for the company wrote in an email to TechCrunch.