[8] In 1962, Prine was cast in the Academy Award-nominated film The Miracle Worker as Helen Keller's older brother James.

[1] In 1962, Prine landed the lead role of Andy Guthrie with Earl Holliman in the 28-episode NBC series Wide Country, a drama about two brothers who are rodeo performers which aired between 1962 and 1963.

[6] After the cancellation of Wide Country, Prine continued to work throughout the 1960s, in such Western television series as Gunsmoke, Bonanza, The Virginian, and Wagon Train.

[10] His other television appearances included the non-Western series Dr. Kildare, Cannon, Combat!, and Twelve O'Clock High.

[11] In the late 1960s, Prine appeared in three prominent films made by director Andrew V. McLaglen: The Devil's Brigade (1968) with William Holden, Bandolero!

These series included Baretta, Barnaby Jones, Hawaii Five-O, The Bionic Woman, W.E.B., Dallas, and as Steven in the science-fiction miniseries V and its sequel V: The Final Battle.

Prine appeared in a succession of cult horror films Simon, King of the Witches (1971), Hannah, Queen of the Vampires (1973), Terror Circus (1973), The Centerfold Girls (1974), The Town That Dreaded Sundown (1976), Grizzly (1976), The Evil (1978), and Amityville II: The Possession (1982).

Prine worked with director Quentin Tarantino on an Emmy-winning episode of CSI: Crime Scene Investigation and in Saving Grace with Holly Hunter, Boston Legal, and Six Feet Under, in addition to feature films with Johnny Knoxville.

The Encore Western Channel has featured him on Conversations with Andrew Prine, interviewing Hollywood actors such as Eli Wallach, Harry Carey, Jr., and Patrick Wayne, and film makers such as Mark Rydell with behind-the-scenes anecdotes.

[citation needed] A life member of the Actors Studio,[13] Prine's stage work includes Long Day's Journey into Night with Charlton Heston and Deborah Kerr, The Caine Mutiny Court-Martial, directed by Henry Fonda, and A Distant Bell on Broadway.

The FBI later determined Kupcinet had delivered to Prine and herself the threatening and profane messages, consisting of words and letters she had cut out of magazines.

Coroner Harold Kade concluded that due to a broken hyoid bone in her throat, Kupcinet had been strangled.

Additionally during the investigation both Edward Rubin and Robert Hathaway, the two men who had been at her apartment the night of her death and possibly been the last to see her alive, were eventually named as suspects.

[citation needed] Later, Lange stopped talking to the police and hired high powered attorneys and moved to New York.