The teenage mother who snapped her toddler son's back last summer was sentenced to prison for murder and child abuse Friday during an emotional court hearing.

Adrianna Lucero, 18, sobbed uncontrollably as she was led from the courtroom after 3rd District Judge Vernice Trease imposed a sentence of 15 years to life for the first-degree felony murder of Alejandro Lucero, who was 2 when he was killed. The judge also sentenced Lucero to 15 years to life for second-degree felony child abuse. The judge ordered that the sentences run concurrently.

Meanwhile, Lucero continued to insist that she was not guilty and suggested her former boyfriend, Sergio Martinez-Gonzalez, was responsible.

"I would never hurt my son," she said, weeping. "I did not murder my child. The murderer is still out on the streets. What child will he go after next?"

Prosecutors insisted Lucero was a stressed-out single mother with three children by the time she was 17 who coldly got rid of the "dispensable" child in her life.

Prosecutors theorized that the toddler was wrecking Lucero's chances to fulfill her version of the American dream, which included a family life with Martinez-Gonzalez, as well as a college degree and a shot at gaining financial wealth.

They noted that Lucero had a fiery temper and broke things when in a rage, and that Alejandro at the time he died had evidence of an older, similar back injury as well as a fractured rib and marks on his face.

Prosecutors also told a jury at the April trial that Lucero repeatedly lied about what had happened to the child to police, paramedics, hospital workers, her sister and her mother.

Defense attorneys, however, painted Lucero as a vulnerable young woman who was physically abused by her lover and who lied to police only to protect him from being deported to his native Mexico because he was here illegally.

Two witnesses testified they saw Martinez-Gonzalez beating Lucero in a car and blocked his way while they called police. He was charged with obstruction of justice, but the charges later were dropped. Immigration authorities, however, were planning to deport him.

Defense attorneys maintained that Martinez-Gonzalez was the person who wanted Alejandro out of the way and this adult male was the person with the physical strength to break Alejandro's spine on Aug. 24, 2008, in Martinez-Gonzalez's basement apartment.

However, the jury found the young mother guilty after just three and a half hours of deliberation.

Lucero, who is a United States citizen, was 15 when she got pregnant with Alejandro by a man who was eventually deported to Mexico. She met Martinez-Gonzalez, had twin boys by him and apparently hoped she could have a future with him despite the fact that she was known to be wildly jealous of his wife and two children in Mexico, with whom Martinez-Gonzalez kept in close contact and to whom he sent money.

Despite the hardships in her life, Lucero was successful in other areas. She managed to take the infants by bus to a day-care program at school, where she excelled, and she was eager to attend college.

e-mail: lindat@desnews.com