The information issue arose again on Wednesday when US officials disclosed that the CIA had placed Tamerlan Tsarnaev on a terrorism watch list several months after the FBI had placed him on a different watch list. Both actions were based on separate alerts provided by Russian authorities, but they failed to help the United States recognize and intervene to head off the threat or identify Tsarnaev as a suspect once the bombs went off.

Also Wednesday, new details emerged about the capture of the younger Tsarnaev brother, Dzhokhar, after Tamerlan was killed in a gunfight with police.

Members of the MBTA SWAT team that arrested Dzhokhar Tsarnaev confirmed that, despite their fears, the 19-year-old bombing suspect did not appear to have a weapon when they finally pulled him from the bullet-riddled boat in a Watertown backyard where he was hiding. He was struggling to remain conscious, and had no weapon on him, they said.

“He looked like a bloodied-face suspect in need of medical care,” SWAT team member Kenny Tran said in an interview with the Globe.

Law enforcement agents said Wednesday they do not believe the wound on his neck was the result of a suicide attempt — contrary to some published reports.

SWAT team member Jeff Campbell said the 2-inch-long bleeding wound on the front of his neck looked more like a cut made by shrapnel from an explosion.

A second law enforcement official echoed the view that the wound did not appear to be self inflicted.

Also Wednesday, Representative Dutch Ruppersberger, a Maryland Democrat and the ranking member on the House Intelligence Committee, said the dual bombs near the Marathon finish line were detonated by a remote control for a toy car. Ruppersberger made his comments after a briefing by law enforcement officials.

In Russia, the news agency RIA Novosti reported Tsarnaev’s parents had agreed to come to the United States to answer questions.

Members of Congress, meanwhile, expressed alarm Wednesday that 12 years of efforts to improve the sharing of information – a federal priority since the Sept. 11 attacks — weren’t enough to track the international movements of bombing suspect Tamerlan Tsarnaev despite a string of suspicions about his actions.

Even though Tsarnaev was placed on two separate terror tracking lists in 2011, the FBI failed to detect his travel to the Dagestan region of Russia for six months in 2012 because his name was spelled wrong on an airline passenger list, according to officials. The Department of Homeland Security did detect his travel.

Senator Lindsey Graham, a South Carolina Republican, said he couldn’t fathom why the Department of Homeland Security apparently knew Tsarnaev was going to Russia, but the FBI did not.

“How could we not know that he was going to Russia, if it pinged at Homeland Security, why didn’t the FBI and other agencies know about it?” Graham said.

“Eleven, twelve years after 9/11, it can’t be such that when you are informed by a foreign government that the person — who actually committed the terrorist attack — may actually have been a terrorist in the making in 2011,” Graham said.

Problems with the government’s information sharing have been known in Washington circles, if not well-publicized. The Government Accountability Office, a federal unit that audits the efficiency of federal programs, reported in January that information sharing remained a “high risk” problem for the US government, the most deficient ranking that can be given in a GAO evaluation.

The “high risk” ranking was first given in 2005 and, despite what the GAO called improvement, enough serious questions remain that the program was again given that ranking in January. The audit has not been widely reported.

White House Press Secretary Jay Carney declined to say at a briefing whether President Obama was confident that federal databases on potential terrorists were working, or whether federal agencies were sharing enough information, or if information was properly followed up, saying those questions would be addressed in an investigation.