As two Boston park rangers continue to recover from being stabbed Tuesday on Boston Common, information is emerging about the man accused of attacking them.

Bodio Hutchinson's criminal past includes drug and assault charges that date back as far as 1999. Hutchinson's history also includes mental illness, and she says he "struggles every day to know what's his reality," his lawyer said.

Only trickles of people are on Boston Common Thursday as afternoon showers move in. Here at the Soldiers and Sailors Monument, there’s no reminder of the scene on Tuesday when Bodio Hutchinson allegedly stabbed two park rangers. Hutchinson was homeless and, according to his attorney, suffers from paranoid schizophrenia.

"Every single person out there has a different story, a different reason they’re on the street," said Lyndia Downie, who runs the Pine Street Inn, which has long provided housing services to the homeless. Earlier this year, Hutchinson was a sporadic resident of the Pine Street shelter. But Downie says workers lost track of him months ago. She says the inability to help those like Hutchinson with a severe mental illness can be frustrating.

"They end up languishing on the street for years," she said. "Many of them don’t do what this man did, but many of them end up with serious health-care issues because they end up on the street."

Over the past 10 years, Boston’s homeless population has increased, but aggressive outreach efforts have helped cut the number of homeless living on the streets by 40 percent.

"I know it doesn’t look that way," Downie said. "Sometimes you walk by and say, 'My God, it looks like more people.' But if you look at the aggregate number, we’ve actually been able to bring it down."

That includes Boston Common, which Downie says for many years hosted a large number of older homeless people. Today, there are fewer of them, but they’ve been joined by a younger group.

"They’re young people, and when I say young, you know, they’re in their early 20s," she said. "But then there’s a group of people who have been on the street a very long time that are still there that we can’t find housing for and we can’t get services for."

It’s those chronically homeless people who fall through the cracks, says Dr. Jessie Gaeta – medical director for the Boston Health Care for the Homeless Program.

"There’s some people for whom even our systems in place — there’s some people for who these systems are really not well utilized or not accessible enough," Gaeta said.

Gaeta says many in this group are often isolated not just from systems of care, but also the support of family and friends. Another problem, she adds, is finding housing that is both affordable and fits their specific needs.

"Not everyone needs supportive housing," she said. "Some people really need access to a subsidy, or maybe some help navigating the housing search and application process. Other people need some kind of service to help them sustain a tenancy."

Five years ago, the Pine Street Inn began focusing on more permanent housing rather than emergency shelters. In one of its homes, 96 percent of residents who were once chronically homeless are still there.