(AP)- - U.S. and Iraqi forces drastically tightened security across Baghdad on Saturday in advance of the expected guilty verdict against Saddam Hussein, and the Iraqi prime minister said he hoped the ousted dictator would "get what he deserves."

Hussein, the former Iraqi leader, has been on trial for murder and crimes against humanity. If convicted, he could be sentenced to death by hanging.

Violence already is running high: At least 39 people were killed or found dead nationwide Saturday. Four mortar rounds hit near Iraq's most revered Sunni shrine, the Grand Imam Abu Hanifa Mosque in Baghdad, killing at least five people.

Baghdad police reported finding 15 bodies dumped across the city in the 24 hours ending at 6 p.m. Saturday.

The highly anticipated verdict, planned for today, is expected to set off further bloodshed, underscoring the trial's failure to bring reconciliation to a country fractured ever deeper along sectarian lines.

"We hope that the verdict will give this man what he deserves for the crimes he committed against the Iraqi people," said Prime Minister Nouri al-Maliki, who has said he hopes Hussein is hanged.

An aide to al-Maliki said authorities are imposing a 12-hour curfew on Baghdad and three surrounding provinces. It was to begin at 6 a.m. today. Both cars and people were supposed to be barred from the streets. Baghdad's airport also was scheduled to be closed.

The curfew was planned for all of Baghdad province; Salahuddin province, which includes Hussein's hometown of Tikrit, and the Sunni insurgent hotbeds of Diyala and Anbar provinces.

Leave for all military personnel has been canceled indefinitely and vacationing soldiers were recalled to active duty.

New checkpoints sprang up around main roads, including within the heavily fortified Green Zone that houses Iraqi government offices and the U.S. and British embassies. Larger than usual numbers of policemen and U.S. troops patrolled city streets, while U.S. Army Stryker armored vehicles blocked traffic on both sides of the al-Jumhuriyah Bridge, one of the capital's most heavily guarded because it carries traffic past the Green Zone.

Violence will be met with a stern response, said a spokesman for the Interior Ministry, which commands police.

Many of Hussein's fellow Sunni Arabs are predicting a firestorm if the former president is sentenced to death. On the other hand, the majority Shi'ites, who were persecuted under Hussein but now dominate the government, are likely to be enraged if he escapes the gallows.

Hussein and seven codefendants -- including a half-brother -- have been on trial since Oct. 19, 2005, for their alleged roles in the deaths of about 150 Shi'ites in the town of Dujail after an assassination attempt against the president in 1982.

A second Hussein trial -- for alleged genocide against the Kurds -- began in August.

On Wednesday, one of Hussein's lawyers said a death sentence would "open the gates of hell" for the roughly 140,000 U.S. troops in Iraq.