A high-profile murder case involving one of America's most well-known political families took a dramatic turn Wednesday when a judge ordered a new trial for Michael Skakel, the nephew of Robert and Ethel Kennedy. 

Skakel, who has spent more than a decade behind bars, is accused of killing 15-year-old neighbor Martha Moxley with a golf club in 1975. Twenty-seven years after her death, he was convicted and sentenced to 20 years to life in prison. 

For years, Skakel fought unsuccessfully for his conviction to be overturned. But a Connecticut judge gave Skakel, 53, a chance for a fresh start Wednesday, ruling that the defense during his 2002 trial had been inadequate. 

State's Attorney John Smriga said prosecutors plan to appeal, but are still reviewing the judge's decision. 

Robert F. Kennedy Jr., who has long maintained his cousin's innocence, described the judge's order as a "blessed event." 

"I think everybody who knows Michael's overjoyed with it," Kennedy told CNN's "AC360." 

Martha Moxley's mother said the judge's ruling does nothing to change her mind. 

"There's not a way they can erase what was said during the first trial. ... I have not given up and I do believe Michael Skakel killed my daughter," Dorthy Moxley told CNN's "Piers Morgan Live." "If there is a new trial, I will be there." 

Judge: Defense 'constitutionally deficient' 

In a lengthy opinion Wednesday, Connecticut Appellate Judge Thomas Bishop ruled that defense attorney Michael "Mickey" Sherman's representation of Skakel was "constitutionally deficient." 

"The defense of a serious felony prosecution requires attention to detail, an energetic investigation and a coherent plan of defense (capably) executed," Bishop wrote in his decision. "Trial counsel's failures in each of these areas of representation were significant and, ultimately, fatal to a constitutionally adequate defense." 
Who is accused of killing a neighbor?
Which famous family is he related to?
How many years was he sentenced to?
For the murder of whom?
How old was she?
What was the murder weapon?
In what year did it take place?
How many years passed before a conviction?
Who believes that Skakel is innocent?
How are they related?
Does Moxley's mother agree with Skakel's innocence?
Does she intend to be present at the new trial?
Who was Skakel's defense attorney?
Which judge decided to order a new trial?
What reasoning did he give?
What three things are required of a capable defender?
How old is Skakel currently?
Who plans to appeal the new trial?
According to whom?
How much time has Skakel already served?
Michael Skakel
Michael Skake
Robert and Ethel Kennedy.
the nephew of Robert and Ethel Kennedy. 
20 years to life in prison.
 he was convicted and sentenced to 20 years to life in prison. 
Martha Moxley
, is accused of killing 15-year-old neighbor Martha Moxley
15
 15-year-old neighbor Martha Moxley 
golf club
 with a golf club
1975
 in 1975
27
 Twenty-seven years after her death, he was convicted 
Robert F. Kennedy Jr.,
Robert F. Kennedy Jr., who has long maintained his cousin's innocence,
cousins
 who has long maintained his cousin's innocence,
No
"There's not a way they can erase what was said during the first trial. ... I have not given up and I do believe Michael Skakel killed my daughter,
Yes
 "If there is a new trial, I will be there." 

Michael "Mickey" Sherman's
that defense attorney Michael "Mickey" Sherman's representation of Skakel 
Judge Thomas Bishop
 Connecticut Appellate Judge Thomas Bishop 
representation was "constitutionally deficient."
 Michael "Mickey" Sherman's representation of Skakel was "constitutionally deficient." 
attention to detail, an energetic investigation, and a coherent plan of defense
"The defense of a serious felony prosecution requires attention to detail, an energetic investigation and a coherent plan of defense (capably) executed,
53,
 Skakel, 53,
prosecutors
State's Attorney John Smriga said prosecutors plan to appeal, 
State's Attorney John Smriga
State's Attorney John Smriga said prosecutors plan to appeal, 
more than a decade
Skakel, who has spent more than a decade behind bars, 