How important is supportive housing in helping ex-convicts keep from returning to jail or prison? Just ask one resident of supportive housing whom we'll call Sam. Sam spent years moving back and forth between jail cells and homeless shelters before he moved into a scattered-site development managed by Common Ground Community, Inc., in the Bronx, N.Y., last year. He still struggles with addiction to several controlled substances but so far has managed to stay within the rules of his community and keep his apartment.

"Before having this housing I never had anything that I cared about losing," he said. "I want to get clean."

Supportive housing is making a huge difference for people like Sam. Experts estimate that more than 10 percent of those released from jail or prison will become homeless. Many of these suffer with mental health or substance abuse issues or both and could benefit from supportive housing.

However, former prisoners and jail inmates like Sam are systematically excluded from many supportive-housing communities. As a result, huge numbers cycle through prisons and jails into homelessness and back, again and again. Experts are now trying to get these people the help they need, either by finding or building supportive housing that will accept them or by connecting them with services.

Chronically homeless, chronically incarcerated

As of June, 2.3 million people were locked up in federal or state prisons and jails. More than half report that they suffer from mental health problems, according to the Bureau of Justice.

The mentally ill account for most of the roughly 10 percent of jail inmates who become homeless after their release. Of both state prisoners and jail inmates who had mental health problems, nearly a quarter had previously been incarcerated three or more times, according to the Corporation for Supportive Housing (CSH), a supportive-housing advocacy group.

Jails, in particular, became a dumping ground for the mentally ill after the mass closing of state-run psychiatric hospitals that accelerated in the 1970s and threw tens of thousands of mentally ill people onto the streets. Many are regularly jailed for nuisance crimes like public urination, vagrancy, or possession of illegal substances, although some mentally ill people are sent to prison for more serious crimes with longer sentences.

Repeat offenders who combine mental illness with substance abuse are exactly the type of chronically homeless people supportive housing is supposed to help. Take "Million-Dollar Murray," the chronically homeless Reno, Nev., man made famous in the Feb. 13, 2006, issue of The New Yorker magazine. Murray Barr consumed more than $1 million in emergency room services in his years on the streets and had been arrested dozens of times by the time The New Yorker wrote about him.

"There is a subset of people that are exiting jail or prison; they are guaranteed to go back unless they get support," said Andy McMahon, a senior program manager for CSH. "They don't have the capacity to stay housed or stay out of jail."

But for the most part, apartments at supportive-housing communities are not available to them. Almost all the apartments now in service are supported with rental subsidy provided by Sec. 8 vouchers from the Department of Housing and Urban Development (HUD) or by HUD's McKinney-Vento Homeless Assistance Shelter Plus Care program.

The Sec. 8 voucher program is administered by local agencies, most of which exclude potential tenants with any kind of criminal record.

The McKinney-Vento program doesn't recognize anyone who has just completed a month or more in an institution like jail as homeless. That's because to qualify as homeless, clients need to have been in a homeless shelter within the last 30 days or have a number of stays in the recent past. A jail inmate interested in supportive housing will often have to return to a homeless shelter before becoming eligible for funding.

Also, many supportive-housing properties have long waiting lists. It's difficult for a person who is constantly vanishing into the criminal justice system to work his way to the top of the list.

"The vast majority of supportive housing is not available to people leaving prison or jail," said Richard Cho, associate director for CSH.

Advocates like Cho are pressing housing authorities to make their requirements more nuanced when screening for Sec. 8 voucher funding. In Seattle and Vancouver, Wash., housing authority officials now differentiate between those incarcerated for nuisance crimes and those in jail for more serious offenses.

Officials are paying attention in part because of the clear impact former prisoners and inmates can have on their neighborhoods when they return without help.

Researchers have found that just a few census tracts in some of the nation's biggest cities generate a disproportionate number of the criminals who end up incarcerated.

In many places, the concentration is so dense that states are spending in excess of $1 million a year to incarcerate the residents of a single city block, according to a 2003 study by the Spatial Design Lab at Columbia University. After they get out of jail, these prisoners often return to the same areas.

To help ease the transition back into society, a growing number of local governments, from Chicago to Harris County, Texas, have created Forensic Assertive Community Treatment (FACT) teams. Case workers from the FACT teams work to connect mentally ill jail inmates and prisoners who need support with housing and services after their release.

Services help neglected former prisoners

People returning from prison have typically committed more serious crimes and served longer sentences than jail inmates. They also can get caught up in cycles of homelessness and re-incarceration.

Two-thirds of those released from prison are arrested again within three years of their release, according to the Re- Entry Policy Council, an affiliate of the Council of State Governments. A significant percentage of former prisoners also become homeless, said Cho.

In New York City, La Bodega de la Familia, a local nonprofit, helps returning prisoners connect with stable housing and services. The organization helps its clients appeal to the New York City Housing Authority to be allowed to return to live with their families. La Bodega de la Familia also provides former prisoners with family-based case management, serving more than 1,000 families.

The organization, which also offers walk-in services to people who need them, gets its name from its headquarters, a storefront on the Lower East Side. "Bodega" is a Spanish word usually referring to a small neighborhood grocery store.

The Fortune Society, another New York City nonprofit, provides transitional housing to former prisoners, including many overcoming substance abuse. Last April, Fortune partnered with developer Jonathan Rose Cos. to build a 25,000-square-foot addition to the 62-bed Fortune Academy transitional housing community for former prisoners in Harlem. The addition should be completed by 2011.

"We look at the person, not the rap sheet," said JoAnne Page, president and CEO of the Fortune Society.