Investigators have received dozens of tips from across the country in their search for two convicted murderers who scaled a 30-foot wall and escaped from an Iowa maximum security prison Monday night.

So far, none of the reported sightings of Martin Shane Moon and Robert Joseph Legendre has panned out, said Jim Saunders, spokesman for the Iowa Department of Public Safety.

"We take all the leads very seriously," Saunders said. "But from a practical standpoint, you take the information and evaluate it, and the leads that seem more viable than others get priority. We are still searching for these men."

Moon, 34, and Legendre, 27, are both serving life sentences for murder convictions in the Iowa State Penitentiary in Fort Madison, a small city on the banks of the Mississippi River.

Officials say the men escaped sometime before 6 p.m. using a makeshift rope fashioned from upholstery webbing and a grappling hook.

The tools enabled Moon and Legendre to slip over a section of the prison's limestone wall near a guard tower that had been unoccupied since the day shift ended at 3 p.m., corrections officials said.

Investigators also believe one or both men may have been involved in stealing a car, described as a 1995 Pontiac Bonneville with plates 776-NOW, from a Fort Madison home about 1½ miles from the prison some time after 6 p.m.

Police still do not know whether the prisoners — considered dangerous and dressed in dark clothing — fled together or separately or still have the vehicle.

"What makes us believe they might still have the car?" Saunders said. "The simple answer to that is we haven't found it yet. We're exploring all different possibilities of whether they're together or not."

Law enforcement officials in Illinois and Missouri have joined in the search, while police continue to piece together how the two fled the prison and interview residents who may have seen them, Saunders said. Police have not ruled out that one of the prisoners may be hiding out somewhere nearby.

Moon was convicted of first-degree murder in 2000 for shooting his roommate, Kevin Dickson, in Clarke County in 1999. Court records said Moon, Dickson and others traveled to an abandoned farmhouse near Winterset, allegedly to meet with a drug dealer and that Dickson was shot and killed at the residence.

Legendre, convicted for attempted murder and kidnapping in Nevada, was serving two 15-year-to life sentences and was transferred to Iowa last year. Legendre, formerly of Phoenix, was charged with another man in the near fatal beating of a Las Vegas cab driver. During the attack, police say the driver was struck repeatedly over the head with a hammer and left unconscious.