GROZNY -- The grisly evidence is still splattered on the brick wall of 38 Petropavlovskaya Ulitsa.


The building's residents Thursday directed visitors to the spot in the courtyard where they said two brothers accused of backing the Chechen rebels had been gunned down the day before by men in the camouflage uniforms of Russian Interior Ministry forces.


"They just took them both out and shot them, not for anything," said neighbor Dagmara Ankayeva. "They're beasts, beasts."


With this smoking, half-demolished capital of breakaway Chechnya all but conquered, Russian troops are entering a nasty new phase of their nearly eight-week offensive. They must now impose control over the territory they have taken, over both the largely hostile Chechen civilians and over their own battle-hardened troops.


"Our No. 1 task now is to work with the population," said Colonel Vladimir Mamontov, one of the top Interior Ministry officers in charge of the troops.


Russian officials -- right up to President Boris Yeltsin -- said this week that with the main fighting in Chechnya probably over, the battle for the mountainous republic of about 1 million people must shift now from the regular army to police units, and from fighting to "working with the population."


The question is how. Residents at 38 Petropavlovskaya said the Russians had sent a "death squad" to show people what will happen to those who continue to support Chechen President Dzhokhar Dudayev and the militants who still control much of southern Grozny.


Accounts also circulate among Chechen refugees and officials about Russian soldiers who threaten to throw grenades into basements unless the women and children who have taken shelter there hand out their gold jewelry and other valuables.


Mamontov said he had received "serious accusations" of marauding Russians. He acknowledged they could be true but said none had been proven.


In rare agreement, both Chechen and Russian officers said Grozny is now split between the Russian-held territory to the north and west of the Sunzha and the Chechen-held blocks to the south. And both sides estimate that the heavy fighting in Grozny will only last a few more days before the out-gunned Chechens turn and head for the hills.


It is what will happen afterward that is at issue. Mamontov is planning the martial rule he will help impose after most of the regular army's work is done -- the curfews, restrictions of movement and special passes that will help him hunt down rebel fighters.


Chechen fighters say they are planning a few weeks of lying low, melting into the civilian population. When the weather gets warmer in March and the icy mud now making the roads impassable dries up, they will launch what they expect to be years of guerrilla war against the Russian troops.


Already, even in the areas of northern Grozny that are fully held by Russians, Chechen snipers keep Russian troops nervous. Mamontov said that aside from working with the Chechen population, his main concern now is to clean out snipers' nests and cut off the flow of arms and fighters into Grozny.


Attempts at blocking the arms traffic into Grozny are clearly succeeding in at least one sense -- it has become an exercise in frustration to try to get into the Chechen capital because nearly all the bridges within dozens of miles have been destroyed or damaged by the Russians.