Friday's action follows an announcement earlier this week that the president of the Los Angeles local, Tyrone Freeman, would step aside while the union's national office investigated expenditures disclosed by The Times.
The trustee appointed to take over the local's operations is John Ronches, who has been based in the union's Washington, D.C., headquarters. Ronches, who could not be reached Friday, is an assistant to SEIU Secretary-Treasurer Anna Burger and is a 30-year veteran of the union.
The union also has appointed an outside monitor to review future financial transactions before they are executed.
"We are committed to leading a reform movement within labor, and we will not tolerate any act that puts the interests of our members at risk," SEIU President Andy Stern said in an e-mail.
"As our history shows, when serious factual allegations are brought to our attention, we act swiftly and decisively to ensure that our leadership is being held accountable to our members, who work some of the toughest jobs in America," Stern's statement said.
Freeman could not be reached for comment Friday. He has denied any wrongdoing.
His local, United Long-Term Care Workers, is made up mostly of people who make about $9 an hour tending to patients in their residences and in nursing homes.
SEIU spokeswoman Michelle Ringuette said the union "is going to be looking very closely" into allegations this week that the local leadership retaliated against some staff members when they refused to sign a letter in support of Freeman.
A small number of staffers were transferred to positions far from their homes, and about 10 had their union cellphone service terminated after balking at signing the letter, according to three workers who spoke on condition of anonymity because they feared reprisal.
Ringuette also said the union is examining Times disclosures that the local reported paying $82,000 last year to a Florida video firm that says it never received such a payment. In addition, she said it is reviewing Times revelations that a home owned by Freeman's former chief of staff was used as the address of a housing nonprofit associated with the local, as shown by Labor Department records, interviews and the nonprofit's website.
Freeman and officials of the housing group, which did not receive the tax-exempt status it sought and had lost its right to do business in California, have declined to answer questions about whether the former chief of staff, Rickman Jackson, was paid for the use of his residence.
Jackson, who heads a Michigan local, has not returned several phone calls seeking comment. Last year, the Los Angeles local reported paying him about $133,000 in salary and roughly $45,000 in other, unspecific disbursements, Labor Department filings show.
Two weeks ago, The Times disclosed that the local paid nearly $178,000 to a video firm operated by Freeman's wife at the couple's home, and that his mother-in-law's day-care service had received $96,000 annually for several years from a union-affiliated charity that runs a worker training center.
The local also has paid $16,000 to a now-defunct minor league basketball team coached by Freeman's brother-in-law, and $219,000 to a small video firm run by a former union staffer, Brian Cheatham, records and interviews show.
Three former union employees said in interviews this week that Cheatham has a close relationship with Freeman and his wife.
They identified Cheatham as one of the members of Freeman's wedding party pictured on the website of a Hawaiian nuptials service, www.pacificaisles.com.
Last year, the local spent nearly $300,000 on a Four Seasons Resort golf tournament, restaurants, such as a Morton's steakhouse, a Beverly Hills cigar club and the William Morris Agency, the Hollywood talent firm, The Times reported.