Prince George's County Fire Chief Ronald D. Blackwell, who heads the regional task force investigating a serial arsonist, announced yesterday that he is resigning from his post to take a similar job in neighboring Anne Arundel County.

In a telephone interview yesterday, Blackwell, 52, said a "gracious offer" from Anne Arundel County Executive Janet S. Owens (D) helped him decide to leave Prince George's, a far larger department he joined as a lieutenant colonel five years ago.

"I thought the timing was as good as it was going to get," he said, adding that "the decision was completely mine."

Owens said she received 25 to 30 applications for the chief's job, a position open since March, when Roger Simonds Sr. resigned amid a controversy about overtime pay. Owens said Blackwell was not among the applicants, so she approached him.

"I am very proud of this appointment," Owens said in an interview. "We think Chief Blackwell will bring such strength to the department. We needed a chief with breadth and depth, and we found that in him."

Blackwell's last day is Aug. 20, and he will start his new position three days later. In his absence, the acting chief will be Lt. Col. Darrell Odom, who was brought back from retirement in April at the request of County Executive Jack B. Johnson. Odom, 49, a 24-year veteran of the department, was involved with Johnson's 2002 campaign and his name came up as a possible fire chief in a committee formed after the election, said Tommie Broadwater Jr., who worked on Johnson's transition team.

The county fire chief oversees nearly 1,900 career and volunteer firefighters and paramedics who are assigned to 47 firehouses and who answer about 133,000 calls for service every year. In Anne Arundel, Blackwell inherits a department with about 720 career firefighters that last year answered about 86,000 calls for service from its 27 firehouses.

He also inherits a department that was recently the subject of an internal investigation into overtime spending, which officials there said exceeded the budget by $600,000. Simonds was asked to resign amid criticism of his leadership style and his use of overtime policies, a departure that Owens said left some members of the department demoralized.

"The department has been through a lot," she said. "We hope he brings with him a sense of stability, confidence and competence. We have great strength in this department, but we just need to build on it."

Owens said the department plays an increasingly important role in the county because of its proximity to Baltimore-Washington International Airport, its broad coast line and the state Capitol.

Johnson did not return a call seeking comment about Blackwell's departure, but he said in a statement issued by his office that the county appreciates Blackwell's service and "we wish him the very best."

When Johnson took office in December 2002, he asked for resignations from all department heads but eventually chose to keep Blackwell in place. In April, Johnson helped bring Odom back to the force as one of three lieutenant colonels, essentially a deputy fire chief's post. Odom retired late last year as a major, fire officials said.

Court records show that in 1992, Odom was arrested and charged with simple assault in the District, but the case was dismissed "for want of prosecution."

Vernon Herron, the county's head of public safety and homeland security, said he interviewed Odom and researched his background in the spring. "There is nothing that causes me concern," Herron said. "I have looked into his background, and I am satisfied that he meets all the criteria to be a lieutenant colonel.

"As far as I'm concerned, he has no criminal record."

County officials said Odom will be considered for the permanent job, as will fire majors Lawrence Sedgwick, Mark Bashoor and Carla Blue, all longtime members of the fire department. A county spokesman said a national search is also an option.

Blackwell -- whose starting salary in Anne Arundel is $120,000, about $2,500 more than he is paid in Prince George's -- said he plans to meet with the agency's staff immediately after taking the reins. He said he is "learning and evaluating" his new department, which has a budget similar to that of Prince George's.

"I want to improve on things there that we have accomplished here," he said. "I want to find where the soft spots are in coverage, and I hope to improve the service to citizens there. I need to really look at the resources in place there and determine the best ways to use them."

Blackwell was appointed chief in Prince George's in August 2001, and his first day in his post was Sept. 11, a day that he said made hazardous materials work an even more critical aspect of the department.

Blackwell is perhaps best known in the Washington region as the public face of the Arson Task Force, a multi-agency group investigating the 39 arsons since March 2003 thought to have been set by the same person. He said managers of the task force, which includes 11 local, state and federal agencies, will meet this week to decide on a new spokesman.

Staff writer Avis Thomas-Lester contributed to this report.

Fire Chief Ronald D. Blackwell in March. "The timing was as good as it was going to get," he said of his decision.