Police said that Ms Alavarez’s boyfriend, Frank Deleon Jr, 17, was going to meet her at a park after she found out he was cheating on her with another woman.
Police claim that he allegedly shot the 17-year-old 22 times before fleeing, leaving the dog to run home alone.
Mr Deleon was arrested and charged with murder on Monday night.
“HPD expresses its heartfelt condolences to Ms Alvarez’s family and looks forward to following this case through the courts as we seek justice on her behalf,” the department said in a statement.
ABC 13 reports that gunshots were heard on the night of 11 January, around .30pm. Ms Alvarez’s family members heard the shots and were concerned as they knew the teen was outside.
When the family’s dog, Peanut, arrived home without Ms Alvarez, the family grew worried, prompting the woman’s mother to go looking for her.
Ms Alvarez’s mother found her daughter in an open greenspace near their home.
Detectives reportedly worked with the community to locate Mr Deleon.
Mr Deleon first court appearance was expected on Tuesday.
Investigators are also hoping to interview two individuals seen getting in and out of a dark coloured vehicle that was near the scene the night of the shooting. Those individuals are not believed to have been involved in the shooting.
According to KHOU 11, Ms Alvarez’s stepfather, Tito Mozzygamba, described the teen as a good-natured straight A student who loved to play basketball and volleyball. She reportedly wanted to become a cosmetologist.
A memorial has been set up at the spot where Ms Alvarez was killed.
The family has set up a GoFundMe page to help them with funeral expenses.