CLEVELAND, Ohio -- More than 200 serial rape suspects have been identified based on testing of thousands of rape kits submitted by police departments in Cuyahoga County. Authorities believe they are responsible at least 600 rapes.

The cases have given law enforcement a rare chance-- with hindsight -- to examine the missed opportunities with an eye toward catching the repeat rapists earlier, in hopes of preventing additional attacks.

Some of the rapists went completely undetected until the kits were tested. Others were accused or convicted of many sex crimes over the years but the true extent of their depravity was unknown until recently.

Below are some lessons gleaned from individual cases being handled by the Cuyahoga County Sexual Assault Kit Task Force.

Lesson: More effort is needed to build cases against those who target vulnerable people, who are less likely to believed or push for prosecution.

Example: Daryl Blackmon

Prosecutors say Daryl Blackmon, indicted last month, preyed on victims who were homeless, lived in shelters or were developmentally disabled.

He's pleaded not guilty. Court records show he has mental health issues.

When Blackmon's DNA turned up in several recently tested rape kits, BCI agent Patti Stipek started digging into his past. She found multiple reports accusing him of rape: by a homeless woman he dated, by a relative and by a developmentally disabled man who lived in the same boarding house.

In each report, he was named as the suspect but was never charged. Stipek went back and interviewed those victims to build a case against Blackmon, who she knew was still out on the streets.

Blackmon, 52, is also linked to several additional 1990s rapes that are still under investigation.

The notion that rapists target vulnerable victims who are less likely to be believed isn't new. Prostitutes, drug addicts and the mentally ill have been identified by some criminal profilers as "canaries in the coal mine" when it comes to detecting serial rapists.

But they are often unlikely or unable to stay involved with the criminal justice system. Assistant County Prosecutor Mary Weston said connecting with those victims and helping them through the process is vital to stopping their attackers.

Lesson: Tracking "modus operandi" or MOs over time can help establish patterns, especially in hard-to-solve stranger cases.

Example: Ronald Wheeler

In reality, the 42-year-old might not be the only one to fit that moniker.

A growing number of cases solved after rape kit testing trace back to reports from victims who were using public transportation, though exact figures have yet to be calculated.

It begs the question: Why did patterns like Wheeler's elude law enforcement for years?

Cuyahoga County Common Pleas Judge Dick Ambrose in December sentenced Wheeler to 22 years in prison, after he pleaded guilty to raping the teens, who were 16 and 18 when a man with a gun approached them at bus stops on Lorain Road months apart.

"Come with me if you don't want to get popped," he told one teen, according to her report.

When DNA linked Wheeler to the 1994 rapes, he was already serving a 26-year prison term for a pair of 2007 rapes.

Those two victims were also approached by Wheeler and threatened with a gun as they waited for public transportation. One was at a Rapid Transit stop and the other was at a bus stop.

Besides his four convictions, Wheeler was accused of sex crimes two other times. In 2002, he was found not guilty in a case and in 2003 and a Grand Jury declined to indict him on a rape charge.

Since he was sentenced, Wheeler's DNA has been found in three additional rape kits, according to the Sexual Assault Kit Task Force.

At least one of the victims reported she was kidnapped and raped while waiting at a bus stop. Another was at a Rapid station.

Example: Joe Brown

The 38-year-old is set to appear in court next week.

Investigators say Brown, a convicted drug dealer, approached many of his victims from behind and dragged them into yards or lots to assault them. They were all young, between the ages of 15 and 20 and three of the reported attacks happened along the same 2-mile stretch of Detroit Avenue.

Brown, 38, was set for release from prison in May after serving a four-year sentence for a similar attack on a 15-year-old girl in 2003. He wasn't prosecuted in that case until 2011.

Lesson: Rapists don't always stick to the same types of victims. Some prey on strangers and people they know.

Dwayne Wilson:

A jury convicted Dwayne Wilson last month of raping four women between 1994 and 1997. He was set to get out of prison when rape kit testing connected the 55-year-old to the cold cases.

The rape cases linked to Wilson were geographically diverse but had commonalities, like the use of a knife or a box cutter.

He was even arrested in one of the cases a decade earlier.

Police made efforts to track down Wilson in 1995 after a nurse, waiting alone to catch a bus to work, reported a man with a "carpet cutter" forced her behind a gas station and raped her.

The nurse got her attacker's license plate and when an officer found him, a cutting tool similar to what the 39-year-old woman described was in his trunk, prosecutors said.

Though the reason is unknown, a Grand Jury declined to indict Wilson on those charges. But his name kept popping up in rape investigations.

Meanwhile, Wilson, who worked as a day laborer, was accused of sex crimes at least three other times, including convictions in 1998 and 2009. In those cases his victims were girls, aged 11 and 14 that he knew.

In 2005, he was linked to a 1997 rape case during a rape kit testing pilot project. But the case was dismissed when the victim did not show up to testify.

Cuyahoga County Common Pleas Judge Nancy McDonnell is set to sentence Wilson next week.

Lesson: DNA testing of rape kits can help link harder-to-solve cases together, giving investigators more information to go on.

Example: Robert Green

Robert Green was on oxygen when police went to arrest him in 2013 for the rapes of five women reported over a decade starting in 1993. Many of the attacks were reported in the same East Side neighborhood, near St. Clair Avenue and East 152nd Street. Victims gave somewhat similar descriptions of their attacker. Other than that, there wasn't much evidence to tie the attacks together. And Green's only conviction locally was for carrying a gun into an airport.

There was only one clue, an address. One of Green's earliest victims had called detectives with an address where she'd seen him. Armed with that, Cleveland Det. Karl Lessmann searched for names and then driver's license photos and men who had lived there.

By the time Green's case was ready for trial, DNA had connected him to two more rapes, bringing his total to seven known attacks.

Last year, Judge Pamela Barker sentenced the 69-year-old to 135 years in prison.

Lesson: DNA collection at arrest is vital to linking suspects to unsolved crimes.

Example: Larry McGowan

A simple DNA swab collected by Akron police did what billboards and press coverage could not. It linked Larry McGowan to six rapes and at least one murder.

McGowan was charged last year with raping four women and the murder of Maxine Pratt in 1997. Pratt, 41, was found bludgeoned to death near E. 87th Street wedged under a semi-trailer. She had been raped and her body was run over with a car. He is also a suspect in the 2010 death of 69-year-old Reydonia Harris.

McGowan, however, has not been charged in Harris' death.

Last week, he was indicted on charges he raped two additional women - one in 1996 and one in 1998.

Lesson: If gone unchecked, some serial rapists will escalate to other violent crimes, like murder.



Example: Elias Acevedo Sr.

Acevedo was the first sex offender identified as part of the rape kit testing initiative to admit to murder.

In 2013, Acevedo confessed that he killed kidnapped, raped and killed two women, Christina Adkins and Pamela Pemberton. He knew both women but had not previously been connected to their deaths.

In 1993, a sister-in-law reported Acevedo raped her in a field near where Pemberton's body was later found. The woman said she was pressured by family members not to press charges but changed her mind when investigator approached her about the results of recently tested rape kit.

The investigation also led to Acevedo pleading guilty to repeatedly sexually assaulting three of his daughters. The daughters said they told social workers and police of the abuse a decade earlier but for unknown reasons their father was never arrested or prosecuted. The Plain Dealer requested the police file in the case last year but the city has not provided it.