The Coast Guard has given up search efforts in the case of a well-known oncologist who went missing after boarding his boat in Florida.

Authorities say Dr. Chaundre Cross, 49, of Naples, Florida, was last seen heading out to sea on Aug. 10. His 33-foot Sea Rayn was recovered the next day, but he was nowhere to be found. After three days, 100 hours of scanning 13,100 square miles of air and sea, the Coast Guard suspended the search.

Dr. Chaundre Cross, 49, of Naples, Florida, was last seen heading out to sea on his boat on August 10, 2022. (Photos: Twitter/Collier County Sheriff)

“It is always a difficult decision to suspend a search and rescue case,” Capt. Michael Kahle, the commander of the Coast Guard’s St. Petersburg sector, said in a statement Sunday. “Our deepest sympathies and condolences go out to the family and friends of Dr. Cross during this difficult time.”

Cross is a radiation oncologist who specializes in prostate, breast and brain cancers, his LinkedIn page says. He is a “national expert in prostate, breast and brain cancers,” according to his employer, GenesisCare. Cross is Harvard-trained and serves on national advisory boards for the pharmaceutical companies Pfizer and Johnson & Johnson. He has also served as the chairman of NCH Healthcare System’s cancer committee.

The Collier County Sheriff’s office said the doctor was spotted leaving Naples Bay Marina around 7:30 a.m. His boat with “Vitamin Sea” on the back was found “adrift 16 miles south of Sanibel Island,” the Coast Guard said. The island is about 155 miles south of Tampa, in the Gulf of Mexico, The Miami Herald reports. Other reports show that Cross’ wife, Sarah Jo, filed for divorce the day he left on his boat. However, authorities have not mentioned the dissolution of the marriage or foul play as a factor.

Cross comes from a prominent family. His grandfather was a county judge in Kansas. His mother was a classical violinist who played alongside Sammy Davis Jr., Beyoncé, Led Zeppelin and others, according to her 2014 obituary. She was married to his father, Dr. Cartrell Cross, a pulmonologist in Naples, for 45 years before she died. The couple raised their five children in Houston, Texas.

“He hasn’t returned and family members are concerned,” the sheriff’s office said on Twitter.