Wellington's attorney, Loni Deland, said his client has always had an interest in medieval England and wants to write about it.
"I said, 'Why that name?' and she said 'It sounds so British. I can pass myself off as writing about medieval England,' " Deland said.
Deland said Wellington will keep her former name for paying bills and purposes of Social Security.
"I call her Teresa Bassett and will continue to do so," Deland said.
Deland has denied his client participated in compiling and distributing the list of 1,300 suspected undocumented immigrants, their addresses, telephone numbers and birth dates. The Utah Attorney General's Office continues to investigate the case, and no criminal charges have been filed.
Copies of the list, which included some Social Security numbers, were mailed to law enforcement and news outlets in July. Wellington and Leah D. Carson were employees at the Utah Department of Workforce Services and are under investigation for compiling the information from people they believed to be undocumented immigrants who applied with DWS for benefits for themselves or their family.
Last month, investigators took biological and handwriting samples from Wellington.
State law allows someone to change their name if they are not on probation or parole and are not on a sex offender registry. The law specifies a name change does not affect any pending legal action.