(CNN) -- A controversial hearing got under way in Washington Thursday to examine the alleged radicalization of American Muslims -- a hearing that many Muslim groups have criticized as unfair to the Muslim community.
The number of cases of U.S. citizens or residents charged with or convicted of taking part in terrorist activities has jumped in recent years, according to a recent study from the New America Foundation and Syracuse University. There were 76 such cases in 2009 and 2010 -- nearly half the total since the terror attacks of September 11, 2001, the study says.
But Muslim Americans also have played a role in stopping such plots, said Peter Bergen, a CNN national security analyst. More than 20% of post-9/11 terror investigations in the United States involving Islamic extremism began with tips from Muslim community members or involved cooperation from the family members of alleged plotters, he said.
Here's a look at some recent high-profile cases involving radicalized American Muslims.
Maj. Nidal Hasan
The American-born Army psychiatrist is accused of killing 13 people and wounding 32 others in a November 2009 attack at Fort Hood, Texas. Witnesses at a preliminary hearing identified Hasan as the man they heard shout "God is great" in Arabic before he opened fire with a handgun. Hasan fired more than 200 rounds, authorities allege, before he was shot by police. He is partially paralyzed, from the chest down, and uses a wheelchair. He faces a likely court-martial and the possibility of the death penalty.
Zazi, an Afghanistan native who worked as an airport shuttle driver in Colorado, pleaded guilty in February 2010 to a plot to detonate explosives in New York's subway system. His father, Mohammed Zazi, has pleaded not guilty to seven charges related to the incident. Three others, including Zazi's uncle, were also charged in the case. Zerin Ahmedzay and Adis Medunjanin pleaded guilty to conspiracy charges and other counts.
Colleen LaRose and Jamie Ramirez
A U.S. citizen and Pennsylvania resident who was born in Michigan, LaRose called herself "Jihad Jane" online. She pleaded guilty in February to charges including conspiring to support terrorists and kill someone overseas. Prosecutors said she was part of a plot to murder Swedish cartoonist Lars Vilks, who outraged some by depicting the Prophet Mohammed with the body of a dog in 2007. Jamie Ramirez, who authorities say was an associate of LaRose's, is charged with conspiracy to provide material support to terrorists. Her trial is set for May 2.
A U.S.-born citizen who lived in Brooklyn, New York, El-Hanafi was arrested April 30 on charges in the Southern District of New York that he conspired to provide material support, including computer advice and assistance, to al Qaeda. Also arrested was Sabirhan Hasanoff, a citizen of both the United States and Australia and a former resident of Brooklyn, New York. He faces similar charges.
A naturalized U.S. citizen from Pakistan and a resident of Connecticut, Shahzad was sentenced to life in prison in October for a botched attempt to set off a car bomb in New York's Times Square on May 1. The bomb failed to detonate, and Shahzad was arrested two days later while attempting to leave the country on a flight bound for Pakistan from New York's John F. Kennedy International Airport.
Hussain, a U.S. citizen and Muslim convert formerly known as Antonio Martinez, was arrested in December for allegedly attempting to detonate an inert device supplied to him by an undercover FBI agent, authorities said. He apparently was upset by U.S. forces killing "Muslim brothers and sisters" overseas, court papers said.
A naturalized U.S. citizen from Morocco and resident of Kansas City, Missouri, Ouazzani pleaded guilty last year to conspiracy to provide material support to al Qaeda and to bank fraud and money laundering. He personally provided more than $23,000 to al Qaeda.
Mohamed Hamoud Alessa
A U.S. citizen and resident of North Bergen, New Jersey, Alessa pleaded guilty in March to charges of conspiring to kill, maim, and kidnap persons outside the United States. Alessa and co-defendant Carlos Eduardo Almonte conspired to go to Egypt as a means of traveling to Somalia, where they intended to join the terrorist organization al-Shabaab and wage violent jihad.
Carlos Eduardo Almonte
A U.S. citizen and resident of Elmwood Park, New Jersey, Almonte was arrested June 5 on charges of conspiring to kill, maim, and kidnap persons outside the United States. Almonte conspired to go to Egypt as a means of traveling to Somalia, where he and Alessa intended to join the terrorist organization Al-Shabaab and wage violent jihad.
Zachary Adam Chesser
Chesser was sentenced to 25 years in prison in February for posting online threats against the creators of the animated TV series "South Park." He encouraged violent jihadists to attack "South Park" writers for an episode that depicted the Prophet Mohammed in a bear suit, court documents said. He posted online messages that included the writers' home addresses and urged online readers to "pay them a visit," the documents said. He also attempted to join al-Shabaab, authorities said.
Nima Ali Yusuf
Yusuf, of San Diego, California, was indicted last year on charges of conspiring to provide money and personnel to terrorists and the Islamic extremist group Al-Shabaab, federal authorities said. She also is charged with making false statements to federal agencies in a matter involving international terrorism, prosecutors said.
Said Omar and others
Eight Somali-American men from Minnesota were charged in November with federal terror-related counts involving al-Shabaab. The alleged offenses include providing financial support to those who traveled to Somalia to fight for al-Shabaab, attending terrorist training camps operated by the group and fighting on behalf of al-Shabaab.
Mohamed Osman Mohamud
Mohamud, 19, a naturalized U.S. citizen from Somalia, was arrested in November and has pleaded not guilty to a single count of attempting to use a weapon of mass destruction. A student at Oregon State University, Mohamud allegedly attempted to detonate what he thought was an explosives-laden van parked near a holiday tree-lighting ceremony in Portland, Oregon's Pioneer Courthouse Square, authorities said. The bomb was fake, thanks to an undercover operation designed to undermine the plotter.
A Muslim convert from Memphis, Tennessee, Muhammad allegedly opened fire June 1, 2009, on a Little Rock, Arkansas, military recruiting center, killing two people. Muhammad, who was 23 at the time, was angry at the U.S. military because of "what they had done to Muslims in the past," said Little Rock homicide detective Tommy Hudson. He is charged with one count of capital murder and 16 counts of engaging in a terrorist act, and is awaiting trial.
Hosam Maher Husein Smadi
Husein was sentenced to 24 years in prison in October after he was caught in an FBI undercover operation trying to use a truck bomb to destroy the 60-story Fountain Place office building in Dallas. He pleaded guilty to attempted use of a weapon of mass destruction. He told agents he wanted to commit violent jihad and was a soldier of Osama bin Laden but authorities found no tie between him and any terrorist group.
Umar Farouk Abdulmutallab
Abdulmutallab faces an October trial for allegedly trying to blow up Northwest Airlines Flight 253 on its final approach to the Detroit airport on December 25, 2009. The Nigerian national has been indicted on charges that include attempted use of a weapon of mass destruction, conspiracy to commit an act of terrorism and possession of a firearm or destructive device in furtherance of an act of violence. He has pleaded not guilty. Prosecutors allege he attempted to ignite an explosive device that was hidden in his underwear. U.S. officials believe al Qaeda in the Arabian Peninsula was behind the alleged bombing attempt.
Khalid Ali-M Aldawsari
Aldawsari, a 20-year-old who attended school near Lubbock, Texas, was arrested last month for allegedly acquiring chemicals to make a bomb and allegedly researching targets including the Dallas home of former President George W. Bush, nuclear power plants and hydroelectric dams. He was arrested on a federal charge of attempted use of a weapon of mass destruction in connection with his alleged purchase of chemicals and equipment necessary to make an improvised explosive device, the Justice Department said. His defense attorney has said the Saudi national plans to plead not guilty. In a personal journal found in Aldawsari's apartment, he wrote that the events of September 11, 2001, had produced a "big change" in his thinking and that he had been inspired by the speeches of al Qaeda leader Osama bin Laden, according to an affidavit.
Russell Defreitas and Abdul Kadir
Defreitas, a 67-year-old former cargo worker at New York's John F. Kennedy International Airport and a native of Guyana, was sentenced to life in prison last month for plotting to explode fuel tanks and a fuel pipeline at the airport. Kadir, a former member of the Guyana parliament, was sentenced to life in prison for the same plot in December. A third man, Kareem Ibrahim, a native of Trinidad, is awaiting sentencing. Authorities said during the trials of Kadir and Defreitas that the men tapped into an international network of Muslim extremists to develop the plot and start working toward carrying it out.
'Liberty City' terrorists
Five Florida men were sentenced in November to prison for plotting terrorist acts with al Qaeda. Seven suspects were arrested in June 2006 for allegedly conspiring to blow up buildings including the 110-story Chicago building then known as the Sears Tower, the FBI's Miami office and others. Five were convicted in a third trial after juries failed to reach a verdict on two previous attempts. The sixth and seventh were acquitted. The suspected ringleader, Narseal Batiste, was sentenced to 13 and a half years in prison plus 35 years of supervised release. The others' sentences range from six to more than nine years in prison. On a surveillance tape played during his trial, Batiste could be heard saying he was grateful to bin Laden and "loved" his work. Authorities said the group's plans appeared to be "more aspirational than operational."