Vicente Ventura Aguilar has been missing since early October. Credit : Credit: Courtesy Felipe Ventura Aguilar NEED TO KNOW A 44-year-old man was dancing with a friend just minutes before he was reportedly detained by immigration agents in Los Angeles on Oct. 7The next day, he experienced a medical crisis as he was being transported to his home country of Mexico, and hasn't been heard from since"We only hope to God that he’s alive,” the missing man's brother said A 44-year-old Mexican man has been missing for more than a month after, his family believes, he was taken into custody by immigration enforcement in Los Angeles in early October — though the federal government maintains that isn't the case. “We’re sad and worried,” Felipe Aguilar told The Los Angeles Times of the disappearance of his brother, Vicente Ventura Aguilar, following Vicente's suspected arrest on Tuesday, Oct. 7. Vicente entered the U.S. around 2008, the Times and MS NOW reported. He does not have legal permission to stay in the country. “He’s my brother and we miss him here at home," Felipe told the Times. "He’s a very good person. We only hope to God that he’s alive.” Vicente was seen on video smiling and dancing on Oct. 7 minutes before he was detained by immigration officials, witnesses told the Times and MS NOW. He left home that morning for a job interview before encountering some friends, the Times reported. MS NOW also reviewed video surveillance from a business at a strip mall in L.A. that shows Vicente dancing with a friend on the sidewalk about five minutes before masked agents arrested people in the area, though he was not seen himself on camera being taken into custody. Vicente subsequently had a "medical emergency" while at an immigration checkpoint at the southern border, a witness told MS NOW. “The whole family is worried, especially our mother in Mexico,” Felipe, his brother, told MS NOW. “We’re afraid that he’s dead.” Vicente was taken to B-18, a short-term holding facility at a federal building in downtown L.A., a friend who was also detained with him said, according to the Times. The following day, a group of detainees was transported to the U.S.-Mexico border and was inside an immigration checkpoint when Vicente was seen shaking and losing consciousness before hitting the ground while he was wearing shackles, the Times reported, citing Vicente's brother and lawyer. He was left with a bleeding face, and the other detainees were told to leave the room and he was taken away for medical care. “His arms and legs were shaking really bad,” the witness, who has since been deported to Mexico, told MS NOW. “He looked like he was dying.” The Department of Homeland Security tells PEOPLE in a statement that during Oct. 7 and Oct. 8, 73 people from Mexico were arrested in L.A. but “none of them were Ventura Aguilar,” spokeswoman Tricia McLaughlin says. “For the record, illegal aliens in detention have access to phones to contact family members and attorneys,” she adds. McLaughlin pointed to an online locator system that families of detained migrants can use but did not respond to questions from PEOPLE about whether authorities have searched for Vicente more thoroughly, including under other names, and if they know where he is now. She criticized "baseless smears" such as "accusations of ICE disappearing people." The incident is one of many arrests that have come as part of President Donald Trump’s promised immigration crackdown, which he campaigned on. The large-sale detentions and deportations have faced a mixed public reaction, polling shows. People protest against ICE immigration raids in Los Angeles in June. Mario Tama/Getty Attorney Lindsay Toczylowski, who represents Vicente’s family, told the Times that she has not received a response from DHS after multiple inquiries. “There’s only one agency that has answers,” Toczylowski, co-founder of the Immigrant Defenders Law Center, told the paper “Their refusal ... says something about the lack of care and the cruelty of the moment right now for DHS,” she said. (Toczylowski did not immediately respond to PEOPLE’s request for comment.) Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories. Loved ones of Vicente and their legal representatives have searched hospitals and reached out to local police to file a missing person's report, according to the Times and MS NOW. They think Vicente may have given officials a different name when he was initially detained. Vicente Ventura Aguilar. Credit: Courtesy Felipe Ventura Aguilar Rep. Sydney Kamlager-Dove has also helped investigate his disappearance by reaching out on the family’s behalf: She wrote a letter last week to the leaders of ICE, DHS and U.S. Customs and Border Protection and pressed for answers. She questioned if federal officials had searched for a person matching Vicente’s description but with a different name spelling or listed under an alias. She also asked for information about anyone who experienced a medical emergency while in ICE custody and if such an individual matched Vicente’s description. “No family should ever have to wonder whether their loved one has been lost — or worse — while in the custody of CBP or ICE,” Kamlager-Dove said in a statement. Rep. Sydney Kamlager-Dove. John Sciulli/Getty Toczylowski took a sharper view. “Mistakes get made," she told the Times. "Right now, what we want to know is what mistakes were made here, and where is Vicente now?”