Three 19-year-old students -- two Kazakhs and an American -- were charged Wednesday with covering up for the suspected Boston marathon bombers, the U.S. Justice Department said.

Dias Kadyrbayev and Azamat Tazhayakov were accused of conspiring to destroy a laptop and backpack containing fireworks belonging to the suspected bombers.

Russian authorities secretly wiretapped the mother of the Boston bombing suspects and recorded her discussing jihad in vague terms during a 2011 telephone conversation, CNN reported Saturday.

The Russians only turned over the information to their U.S. counterparts in recent days, according to the report.

The brothers suspected of carrying out the deadly attacks on the Boston Marathon planned to head to Manhattan to party after the explosions, New York City's police chief said Wednesday.

Either Dzhokhar or Tamerlan Tsarnaev apparently said "Manhattan" in a conversation overheard by the driver of the sports utility vehicle they carjacked in Cambridge, Massachusetts, last week before a showdown with police, Ray Kelly said.

A delegation from the U.S. embassy in Moscow has traveled to the Russian North Caucasus region of Dagestan to interview the parents of the Boston marathon bombing suspects, an embassy official said Wednesday.

The parents of Tamerlan and Dzhokhar Tsarnaev are currently living in Dagestan, an overwhelmingly Muslim region on the Caspian Sea where the family briefly lived before leaving for the United States.

The elder of the two brothers allegedly behind the Boston marathon bombings twice attended boxing training events in Austria, the interior ministry said Tuesday.

Tamerlan Tsarnaev, 26, shot dead on Friday by U.S. police, spent a week in Salzburg in 2007 and a week in Innsbruck in 2009, the ministry said, confirming a media report.

The mother of the Boston bombing suspects was called by the FBI years ago to ask if her eldest son had been radicalized, she said in an interview with a British TV station broadcast on Tuesday.

Zubeidat Tsarnaeva told Channel 4 News that U.S. federal agents had approached her about her eldest son Tamerlan Tsarnaev, 26, who was killed in a shootout with police on April 19.

Boston bomb suspect Dzhokhar Tsarnaev on Monday was charged with using a weapon of mass destruction and could face the death penalty if convicted, the U.S. Department of Justice said.

Tsarnaev, 19, also has been charged with one count of malicious destruction of property by means of deadly explosives, the DOJ said in a statement. He was arraigned in his hospital bed, where he remains in serious condition.

The father of the suspected Boston bombers insisted in an interview published Monday that his sons Tamerlan and Dzhokhar were innocent and could not have carried out the bombings.

Their plans for the future had included returning to work in Russia, Anzor Tsarnaev said in the telephone interview with Komsomolskaya Pravda daily, adding that he hoped to travel to the United States where his younger son Dzhokhar is in hospital after his capture with serious injuries.

Police were seeking answers Sunday from the seriously wounded surviving Boston bombing suspect, amid reports he was responding in writing to questions due to throat injuries.

Investigators who had been waiting to interrogate Dzhokhar Tsarnaev, 19, since his capture on Friday are trying to determine whether his neck wound was self-inflicted in a suicide attempt, USA Today quoted a federal law enforcement official as saying.

With the hospitalized Boston bombing suspect unable to speak, attention shifted Sunday to his dead brother, who may have been radicalized or even trained in the Caucasus last year.

U.S. lawmakers questioned why Tamerlan Tsarnaev, 26, killed in a shootout, did not raise more red flags despite being questioned at the request of a foreign government in 2011 and spending six months in the volatile region in 2012.