Helen Mirren has portrayed various members of English royalty — most notably (and recently) Elizabeths I and II — but for many TV viewers, she always will be Detective Superintendent Jane Tennison, the flinty crime solver who closes baffling cases for the London authorities.

The sleuth's career wraps up with the two-part drama "Prime Suspect: The Final Act," the seventh installment in the suspense series that first aired on PBS in 1992.

"Since then, the police work has changed, with the huge technological advances we've seen," Mirren said. "It has happened that quickly, but the ("Prime Suspect") stories still hold up."

The actress laughed when describing a jarring detail from the first "Prime Suspect" story: a detective brandishing a bulky, early-1990s cell phone.

"Almost everything in 'PS-1' still looks so real and OK, but that cell phone gets you," Mirren said. (By contrast, the finale includes a teenager sending a text message on a cell phone the size of a credit card.)

Mirren shot the last "Prime Suspect" immediately after filming "The Queen," a recent movie that's garnering considerable Oscar buzz for her. She won an Emmy for her role as a mercurial monarch in "Elizabeth I," an HBO miniseries.

When Mirren arrived on the set of "Prime Suspect," according to executive producer Rebecca Eaton, "she walked exactly like the queen. It was like seeing Queen Elizabeth." Eaton, who's worked with Mirren in previous "Prime Suspect" installments, said the actress has created a long-running, complex character who is "so exasperating and irritating, who does things all wrong when she handles people — and yet she is right; she has all the deep determination to find the truth at whatever personal cost."

"There is a little of watching an emotional train wreck when you see Jane Tennison, and at the end of every (miniseries), for her it was worth it," Eaton said.

The series finale centers on a missing girl who turns up murdered. But it also delves into Tennison's life: She's reluctantly edging toward retirement as she faces her father's terminal illness and grapples with a drinking problem.

Her colleagues and bosses encourage her to leave the police force, but Tennison pleads for a chance to solve one last case. She follows leads that go nowhere while denying her alcoholism and provoking a suspect — with tragic results.

"Jane is a vulnerable, flawed person," Mirren said. "Strong women are boring, so I play vulnerable women."

Mirren prides herself on her input in every episode of the series: She chose different writers and directors for each, which allowed every story to achieve the distinct look and feel of a stand-alone drama.

"Creative people are far better when they have freedom and feel personally involved, not that they're just coming onto a successful series," she said. "I loved that the writers would take Jane where they wanted to take her."

The final installment includes a poignant element: Tennison's longtime adversary, former Sgt. Bill Otley (Tom Bell), spots her at an Alcoholics Anonymous meeting and apologizes for having repeatedly tried to sabotage her career. But Otley's return to her life is cut short and, in a sad coincidence, Bell died Oct. 4 after a short illness.

The drama plays out over four hours, which Mirren said gave the cast and crew the luxury of working out every plot detail.