Guinness World Records said it would be interested in hearing from Mr Dean to verify his status as the UK's oldest man.

BBC: 'Oldest man in Britain' celebrates 109th birthday

Instead, the patients received regular follow-up for congestive heart failure, such as appointments with their doctor, and calls every three months to verify their status in the study and to check for such events as unreported hospitalizations.

CNN: Study: Heart patients helped by phone calls

They say the onus is on employers to verify the legal status of their employees.

NPR: U.S. Tax Program for Illegal Immigrants Under Fire