A registered sex offender was caught after accosting and attempting to rape a woman in the Uptown area of Minneapolis late at night, leaving her battered and unconscious in what may have been his second such crime within hours.

Keith E. Washington, 39, of Minneapolis, was charged Tuesday in Hennepin County District Court with attempted first-degree criminal sexual conduct and third-degree assault in the attack early Sunday. He remained jailed in lieu of $500,000 bail before a court appearance Wednesday.

Washington also is suspected in another attempted rape in an alley in the same part of the city fewer than two hours earlier, the county attorney’s office and police said Wednesday. He has yet to be charged in that assault, which also rendered that victim unconscious.

Police apprehended Washington as he walked near the site of the second attack, which occurred about 4:40 a.m. in the 2800 block of Emerson Avenue S., the criminal complaint said.

Washington is registered with the state as a Level 3 sex offender, meaning that he’s considered among those most likely to commit another sex offense.

Residents who live near a Level 3 offender are notified at a public meeting when a person at that level moves in. Washington lives in the 4000 block of Russell Avenue N., about 6 miles north of where Sunday’s attacks occurred.

He was convicted in 2000 of first-degree criminal sexual conduct. In that case, he choked a woman he knew until she passed out at her house in north Minneapolis, then stripped and raped her as her two young children watched. When she awoke, he choked her again until she blacked out.

In 2004, while serving 9 years for the earlier rape conviction, he was convicted and sentenced for assaulting a corrections officer. That assault conviction kept him locked up until this past May, according to the state’s Department of Corrections.

“We believe Mr. Washington is a very dangerous man,” County Attorney Mike Freeman said. “He has a history of choking women until they are unconscious, and it is just good fortune that he hasn’t killed one of them.”

Freeman predicted that Washington will be “going away for a very long time. … What’s tragic about this is that Mr. Washington has done this before, [and] it’s obvious some time in prison didn’t teach him a lesson.”

Freeman added that authorities also are looking into whether Washington is connected to a similar sexual assault on Nov. 22 in an Uptown parking ramp. In that attack, witnesses found a partly undressed woman about 9 p.m. “lying unconscious near her running vehicle” at the Calhoun Square ramp next to the shopping center at Lake Street and Hennepin Avenue S., according to police. The woman said she did not remember anything.

According to the charges in the second assault on Sunday, officers called about a rape in progress found the 28-year-old victim unconscious on a front yard. Her neck was marked and bruised.

When police roused her, she gasped for breath and said, “He raped me,” according to the complaint.

The woman said that she had been visiting nearby bars with her sister and that the two had argued. While on the phone outside to call another sister for a ride home, Washington approached her and became a bother, the charges said.

He walked with the woman for a couple of blocks and then tackled her, choking her until she blacked out, according to the charges. She awoke to find herself partly undressed and her cellphone gone.

Two adults told police that they saw the attack unfold and that Washington said the woman was “fine” before he “pointed something menacingly at them.”

Officers searching the area came upon Washington within 30 minutes, carrying the victim’s cellphone and identification card. They also discovered that he had a cellphone, identification card and bag of groceries reportedly taken a few hours earlier from the earlier sexual assault victim in the Uptown area.

That woman, 26 years old, told authorities she had been choked into unconsciousness before the assault. Police said she had been attacked about 3 a.m. in an alley in the 2400 block of Colfax Avenue S.

Washington told police he had gotten lost after visiting several bars in the area and then found a woman moaning on the ground. He said he kicked her “to see if she was all right” and told a man to call police because he thought she was drunk.

Along with the sex crime allegations, Washington has a long list of convictions for offenses involving violence and illicit drug use that span nearly all of his adult life, at times occurring while he was serving time.