LONDON — President Robert G. Mugabe of Zimbabwe has appointed a former security strongman nicknamed the Crocodile to replace his dismissed vice president, Joice Mujuru, according to news reports.

The purge of Ms. Mujuru and elevation of Emmerson Mnangagwa, the current justice minister, figure in the closely watched maneuvering over who will eventually succeed the autocratic Mr. Mugabe, who is 90 years old.

Many Zimbabweans see Mr. Mnangagwa, 69, as a hard-liner who has been close to Mr. Mugabe for half a century and has played a critical role in his ruthless suppression of dissent. He has also emerged in recent months as an ally of the president’s 49-year-old wife, Grace Mugabe, in a ferocious campaign to discredit Ms. Mujuru, who once was seen as Mr. Mugabe’s heir apparent.

Political analysts say the changes at the top — which included the dismissal of at least seven cabinet ministers along with Ms. Mujuru on Tuesday — are meant to ensure that Mr. Mugabe’s family and their business interests are shielded from the turmoil that is likely to follow his death.