Criminalist Testifies in Sexual Assault Case


YoloCourt-26By Ryan Gonzales

On Friday, December 9, the prosecution rested their case in the People v. Patricio Rosas, with their final expert witness, Lisa Langford, a criminalist for the California Department of Justice.

Mr. Rosas is being charged with multiple counts of sexual assault on a minor, based on the allegations that he continuously sexually assaulted his wife’s daughter.

Ms. Langford testified that she performed the DNA extraction of multiple evidence that was obtained from investigators, such as a white rag found in Mr. Rosas’ car and segments of carpet from his apartment.

Deputy District Attorney Michelle Serafin brought out the white rag, known as People’s Exhibit 27, for Ms. Langford to identify. Ms. Langford showed the jury the two holes where her fellow colleague had cut out portions of the rag for DNA testing. Ms. Langford testified that these two segments had stains that appeared to contain semen and blood.

Prior to performing the test, Ms. Langford had obtained buccal swab samples from the alleged victim and Rosas, which she had used for reference when determining the identity of the DNA samples. Thus, when Ms. Serafin asked if Ms. Langford was able to establish a full DNA profile, she testified that, by using the buccal samples, she was able to find a match with one of the rag segments.

“The results provide strong evidence that the fluids (semen) came from Patricio,” stated Ms. Langford.

Then Ms. Serafin questioned whether she had found any other non-seminal fluids within the stains, and Ms. Langford told the court that there were three non-sperm DNA fragment contributors. However, the alleged victim was excluded as a major and minor contributor.

Ms. Serafin then inquired about the second stain found on the rag, and Ms. Langford told the court that she was unable to produce a full DNA profile because “the mixture was too complex.”

Furthermore, Ms. Serafin asked if it was difficult making a connection due to the father-daughter relationship of the victim and Mr. Rosas. Ms. Langford responded, “Yes, they share similar DNA types.”

However, in previous testimony, the alleged victim told the court that she only considered Patricio Rosas to be a father figure, but she had identified him as her stepfather, thus they were not related biologically.

During the analysis of the carpet, Ms. Langford testified that all five stains had semen samples that directly matched Patricio Rosas’ DNA profile. Additionally, she testified that the alleged victim was a minor contributor to those stains as well.

However, Deputy Public Defender Peter Borruso questioned whether the DNA that was donated from the alleged victim was consistent with saliva or fluid from a runny nose, to which Ms. Langford responded yes. Yet, Ms. Langford also testified that the stain was consistent with vaginal fluid.

Mr. Borruso then questioned if she had found any blood on the carpet, and to that she responded no.

As Ms. Langford was dismissed and the prosecution rested their case, Judge Samuel T. McAdam told the court that the trial will be moving into closing arguments this Monday, December 12, 2016.


About The Author

The Vanguard Court Watch operates in Yolo, Sacramento and Sacramento Counties with a mission to monitor and report on court cases. Anyone interested in interning at the Courthouse or volunteering to monitor cases should contact the Vanguard at info(at)davisvanguard(dot)org - please email info(at)davisvanguard(dot)org if you find inaccuracies in this report.

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