51.   Federal investigators hope to learn what caused a television news helicopter to crash, killing the pilot, setting a business on fire and toppling power lines.

52.   However, investigators hope to find additional information about Yousef and possible links to a broader network that may be involved in international terrorism.

53.   However, investigators hope they can find additional clues about who was behind the New York bombing and other acts of terrorism.

54.   However, investigators hope to find additional clues about who was behind the New York bombing and other acts of terrorism.

55.   However, Russian Northern Fleet commander Adm. Vyacheslav Popov said that investigators hoped to find special recording devices inside the Kursk that could help in the probe.

56.   However, investigators hope they can find additional clues about who was behind the New York bombing and other terrorist acts.

57.   Investigators also hoped to establish the identities of at least some of the victims.

58.   Investigators had hoped Sergei Petrov, the sole survivor of the crash, would be able to help them determine the cause of the crash.

59.   Investigators also hope to establish the identities of at least some of the victims.

60.   Investigators are hoping he will be able to help them determine the cause of the crash.